Cardiac Catheterization in Congenital Heart Disease: Pediatric and Adult - Part 7 ppt

CHAPTER 22 Intravascular stentsageneral information
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Encore™ indeflator device
The Encore™ device (Medi-Tech, Boston Scientific, Natick,
MA) has a clear polycarbonate syringe barrel encased in a
covering that holds an analog manometer. The manome-
ter is attached to the syringe lumen and has a maximum
pressure of 26 atms. The syringe has a capacity of 20 ml.
The ratchet mechanism on the syringe plunger is engaged
all of the time unless deliberately released by compressing
a squeeze/release button on the side of the barrel.
B. Braun™ angioplasty inflation device
The B. Braun™ angioplasty inflation device (B. Braun
Medical Inc., Bethlehem, PA) has a 25 ml clear polycar-
bonate syringe barrel with an analog pressure gauge,
which reaches and holds 30 atms pressure. The syringe
has a rapid action “winged” locking mechanism, which
locks very quickly, adjusts very accurately and holds at
high pressures.
Merit Medical™ inflation devices
Merit Medical (Merit Medical Systems, Salt Lake City, UT)
has four different inflation devices, all with a clear 20 ml
polycarbonate barrel. The syringe has a squeeze “bar”
on a “T” handle to release the ratchet mechanism. The
difference in the four inflation devices is in the type
of manometer gauge. All of the gauges are electronic, but
are available in analog or digital and in local or remote
configurations and with, or without, built in timers.
Bard Max 30™ inflation device
The Max 30™ (C.R. Bard, Inc., Covington, GA) has a “T”
shaped handle over the polycarbonate barrel of a 20 ml

capacity syringe. A lever which moves from side to side
across the “T” locks or releases the ratchet mechanism
of the syringe. The Max 30™ inflation devices can deliver
30 atmospheres of pressure.
The only additional criterion for the use of any of these
inflation devices is that the operator must be very familiar
with the operation of the specific device that is being used.
Technique for the implant of intravascular
stents
The technique for the delivery and implant of the J & J™,
Palmaz™ stents (Johnson & Johnson, Warren, NJ) has
been developed and modified extensively during the
fifteen years of the clinical use of these stents in congenital
and pediatric cardiac patients. Unfortunately, the stent
and balloon technology for this “non-approved” use has
not kept pace adequately with the complex congenital
lesions for which stent therapy now is routinely utilized.
Relative to the developments in stents and stent tech-
niques for coronary arteries, the stents and delivery
equipment for congenital lesions are a decade behind in
development and in their introduction for clinical use in
the United States. There have been some improvements
in the stents which are approved for use in adult periph-
eral vascular disease and which have filtered down to the
pediatric/congenital population. At the same time, the
changes/improvements in the delivery/implant tech-
niques for congenital heart patients were developed pre-
dominately in pediatric/congenital catheterization labor-
atories during the decade and a half of the use of stents
in these patients.

All “self-mounted” or “hand-mounted” stents are cur-
rently delivered through or with the use of a long sheath
advanced to and past the lesion where the stent is to be
implanted. To date, there are no satisfactory ways of
hand-mounting stents and securing them tightly enough
on the balloons to allow confident and safe delivery of a
stent without the use of a long sheath. Even if secured to
the balloon, without the use of a long sheath, the stiff,
sharp exposed ends of a rigid stent that is hand-mounted
on a balloon, easily extend off the balloon, catch on in-
travascular structures, and are displaced off the balloon
during its passage through the vascular channels to the
lesion. If the stent catches on structures as the stent/
balloon is being advanced, the stent is displaced prox-
imally on the balloon catheter. This prevents delivery to
the lesion and creates a problem in getting the stent out
of the vessel and body, but usually does not result in an
errant, free-floating stent. If the stent catches on structures
during the withdrawal of the balloon/stent/catheter, the
stent is displaced onto the wire distal to the balloon.
Without sophisticated and difficult retrieval techniques,
this results in a stent potentially free floating in the circula-
tion! At present, a long-sheath technique is recommended
and is always used for the delivery of hand-mounted
stents.
The equipment and techniques for the delivery of all
of the available large diameter, hand-mounted stents to
the proximal pulmonary arteries, to the central systemic
veins, and to the large systemic arteries are almost ident-
ical, although the delivery to the pulmonary arteries is

usually more complex and difficult. The similarities in the
equipment, and the general techniques for the delivery
and implant used for all of the stents currently available
for the larger vessels are described in this chapter. The
delivery and implant of the rigid Palmaz™ P _ _ 8 and
P _ _ 10 stents are the most difficult and dangerous.
Familiarity with the techniques for delivering those stents
should make the delivery of most other stents relatively
straightforward. The availability of pre-mounted large
CHAPTER 22 Intravascular stentsageneral information
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stents on appropriate sized balloons may change these
techniques dramatically within the next few years.
The peculiarities and particular difficulties with the
delivery of stents to specific locations in specific vessels
are discussed in Chapters 23, 24 and 25, which cover the
use of intravascular stents in pulmonary arteries, systemic
veins and systemic arteries, respectively. Peculiarities in
the general delivery of the newer, more recently available
stents are discussed at the end of this section on technique.
General technique for stent delivery
Most intravascular stent implants in congenital heart
patients can be performed with well controlled, deep
sedation and liberal local anesthesia. However, since the
procedures can be very long, which becomes uncomfort-
able for the patient, general anesthesia often is used elect-
ively. General anesthesia becomes essential when the
implant of a stent or even part of the procedure is per-
formed from the neck, when it is known that the proced-
ure definitely will be of a very long duration, or when

the patient needs endotracheal intubation for some other
reason. General anesthesia has the advantage of another
physician besides the catheterizing physician monitoring
the patient and having some responsibility for the patient’s
degree of sedation and the control of the patient’s airway.
With the use of either sedation alone, or when general
anesthesia is used, the patient requires a secure intra-
venous line for the administration of supplemental seda-
tion and other medications during the procedure. Often,
just before the actual expansion of the stent for implant and
even though the patient appears sound asleep, the patient
is given a supplemental dose of sedation/anesthesia in
order to ensure that the patient remains absolutely still at
the moment of implant.
All patients undergoing stent implant have an
indwelling arterial line in place during the entire proced-
ure. This line allows instantaneous and continuous moni-
toring of systemic blood pressure and the obtaining of
necessary blood gases throughout the procedure. It al-
ways is better to anticipate and, in turn, to prevent prob-
lems with the patient than to try to compensate for a
catastrophe once it has occurred. A subtle change in the
continuously displayed intravascular blood pressure
which is on a monitor provides an early indicator of
impending trouble, while the periodically displayed pres-
sure from a “cycling” arm blood pressure cuff recorder
may well appear long after the adverse event begins.
Every patient undergoing a stent implant has an
indwelling bladder catheter (Foley™) placed at the begin-
ning of the procedure. No amount of sedation or analgesia

compensates for the discomfort of an over-distended uri-
nary bladder during a long procedureaparticularly if it is
unexpectedly long!
In a patient undergoing stent implant in the pulmonary
arteries or systemic venous systems, one extra venous
catheter is introduced into the venous system in addition to
the venous line(s) which will be necessary for the delivery
of the stent(s), in order to have an extra catheter in the
venous system in addition to the number of catheters
through which stents will be delivered. Thus, in a patient
in whom two stents are to be implanted simultaneously,
three venous catheters are introduced. A separate line is
used for each individual stent delivery, while the additional
venous line is used to perform precise selective angiograms
pre, during, and immediately after the expansion of and
implant of the stent. The additional, angiographic catheter
is positioned in the same vessel, close in proximity and
proximally in the flow of blood to the stenosis/stent
implant area.
Some operators advocate performing the “placement”
angiograms during the stent implant through the long
delivery sheath after the sheath has been withdrawn off
the stent/balloon combination and back into the more
proximal vessel. This technique is of no use during the
positioning of the stent/balloon combination before it
is completely out of the delivery sheath (and no longer
retrievable). Often the details of the anatomy from
angiograms with injections through the sheath are not
suitable. The shaft of the balloon catheter fills and com-
promises most of the lumen of the sheath and the pressure

of the injection through the side port of the sheath is
limited by the loose “seal” of the back-bleed valve of the
sheath over the shaft of the catheter. As a consequence, a
sufficient amount of contrast cannot be delivered rapidly
enough with a high enough pressure to visualize the
stenosis–stent relationships accurately.
In addition, in order to perform the angiogram through
the sheath during the stent implant, the sheath must be
withdrawn completely off the balloon and not just off the
stent. Once the sheath is completely off the balloon/stent,
further readjustment of the stent/balloon position is more
difficult. In addition, this places the distal tip of the sheath
very proximal to both the stent and the area of stenosis in
the vessel. As the contrast is injected relatively slowly
through the sheath and into the more proximal vessel, the
contrast is diluted by adjacent, rapidly flowing blood, pre-
venting an adequate visualization of the area of interest.
Also when the sheath tip is far proximal to the area of
stenosis, the tip is often proximal to a bifurcation or a large
branching vessel, in which case, the majority of the small
quantity of slowly injected contrast is diverted into the
branch vessel and away from the stenotic area. Poor
angiographic imaging is more “the rule” than the excep-
tion with the “through-the-sheath” technique and, as a
consequence, this technique is not recommended. Inad-
equate angiograms compromise the precise positioning
of the balloon/stent.
CHAPTER 22 Intravascular stentsageneral information
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The implant of stents into smaller, more peripheral

veins is the one exception where through-the-sheath
angiograms can be useful. In this circumstance the vessel
is small, the sheath is “upstream” in the flow of blood, the
blood (and contrast) flow is slow and the injection is into a
very confined channel that is being stented. Occasionally,
however, when the implant of a venous stent is “retro-
grade” in the vein (e.g. a stent delivered into a femoral
vein from the jugular approach) the end of the sheath is
“downstream” in the flow from the lesion, with the result
that the contrast injected through the sheath flows away
from the lesion/stent and is of no value.
The area(s) to be stented is(are) identified and quantit-
ated both hemodynamically from the pressure measure-
ments and angiographically with selective angiograms
into the precise vessel/area to be stented. The techniques for
accurate, quantitative measurement are described in detail
in Chapter 11 and definitely should be adhered to for the
implant of intravascular stents. After identifying and
measuring the stenosed area(s) of the involved vessel(s)
very accurately, an end-hole catheter is advanced from the
access site, across and well beyond the area of obstruction. It
is extremely important that the vessel that is entered distal
to the obstruction is of a large diameter and is the longest
distal branch or tributary beyond the stenosis. This vessel
must be long enough to allow the very distal placement of
the tip of the supporting guide wire and of a large enough
diameter to accommodate the distal end of the fully inflated
balloon which will be used to deliver and implant the
stent. When the balloon and stent are centered on the
stenotic lesion during the stent expansion, the distal end

of the implanting balloon will always extend well beyond
the lesion and into the distal vessel. Considerable extra time
is often required to enter this largest, distal vessel. The
extra time spent in locating and achieving a good position
in this largest vessel with the end-hole catheter is essential.
Once the catheter has been manipulated far into the
largest distal vessel, it is replaced with a Super Stiff™
exchange length guide wire. If a long “floppy-tipped”
Super Stiff™ wire is used, the vessel must be very long
(and large enough in diameter) to accommodate the entire
curled up (“balled-up”) long floppy portion of the wire. It
is imperative that the entire, long floppy tip, along with the
transition zone of the wire and a significant portion of the
extra stiff portion of the wire all extend a significant dis-
tance beyond the lesion. The balloon and stent are sup-
ported only by the very stiff portion of the wire and by a
wire that is in a very secure distal position without the
capability of any to-and-fro movement. The precise wire
position contributes significantly to the ultimate success
and safety of the procedure. All the extra time required in
positioning the wire securely and very distally adds to the
likely success of the procedure, while any compromised
location of the wire is inviting a catastrophe.
Over-dilation and tearing of a smaller branch vessel
that is just distal to the stenosis, is one of the greatest haz-
ards during the implant of intravascular stents. It usually
is a consequence of the wire and tip of the balloon being
malpositioned prior to the stent implant. When the bal-
loon tip is positioned and fixed in, and then inflated in, an
erroneous and unusually small vessel that is just distal to

the lesion, either it will rupture the vessel or the balloon
will be “milked” back out of the vessel during the inflation
and, in turn, the stent will be displaced proximally.
When there is a question about the size and configura-
tion of the particular anatomy in the area of the stenosis
and, in particular, a question about the adequacy of the
vessel distal to the stenosis, the anatomy is defined pre-
cisely with a low-pressure, “sizing” balloon. This is not
a pre-dilation of the area but rather, a “zero-pressure”
inflation with a very low-pressure sizing balloon in the
area to determine the contour of the entire area! The most
satisfactory balloon for this sizing is the NuMED™ low-
pressure “angioplasty” (“sizing”) balloon (NuMED Inc.,
Hopkinton, NY), although any angioplasty type balloon
can be used for the sizing if it is inflated only at very low
pressure. The sizing balloon is advanced over the pre-
positioned stiff guide wire and positioned exactly in the
area of stenosis where the balloon/stent is to be inflated.
The sizing balloon is inflated at a very low (zero!) pressure.
The balloon at this “zero” inflation pressure fills, and con-
forms to, the exact anatomy of the stenosis and vessel(s)
both proximal and distal to the lesion without dilating the
area at all. This technique is useful particularly to deter-
mine if there is sufficient diameter distal to the stenosis to
accommodate the distal tip of the balloon during inflation
of the balloon for the stent implant. If the vessel distally
is too small, the zero pressure “sizing” balloon either
does not inflate in the area or it gently “milks” back out
of the vessel. The only disadvantage of this particular
low-pressure sizing balloon is that it requires a 9-French

introductory sheath, but at least this size will usually be
required for the delivery of the stent.
As long as the stenosis is more than 3 to 4 mm in dia-
meter, pre-dilation of stenotic lesions before implanting a
stent is not performed. Only very tight stenoses, which are
too tight to allow a large, long delivery sheath for the
delivery of the stent to pass through the lesion, are pre-
dilated routinely. When pre-dilation is performed, the
stenosis is pre-dilated only enough to allow the particular
delivery sheath to pass through the stenotic area. When
the vessel adjacent to the stenosis (either proximal or dis-
tal to the obstruction) is significantly larger than the pro-
posed initial delivery balloon for the stent, pre-dilation
unequivocally should not be performed. A “successful”
pre-dilation of a stenotic area temporarily will dilate the
area acutely, but it also temporarily makes the area of
the stenosis very compliant and even “patulous”. When a
CHAPTER 22 Intravascular stentsageneral information
562
stent is implanted in this patulous or “softened” area, the
stent does not fix securely to the now elastic walls, even
when it is fully expanded and is in the proper position. As
a consequence, the stent/balloon can be displaced very
easily either during the balloon inflation or, even more
likely, during the attempted removal of the balloon from
within the lumen of the stent after the implant. Any move-
ment of the stent immediately after implant usually
results in migration of the stent to a non-stenosed area of
the vessel or, even worse, results in a stent “free floating”
in a vessel/chamber.

The main argument in favor of pre-dilation of a lesion in
which a stent is going to be implanted, is to ensure that the
balloon/stent combination can open the lesion sufficiently
during the implant/expansion of the stent to allow
removal of the balloon from the stent after implant. The
inability to dilate the lesion during the implant of the
balloon/stent combination can leave not only the original
vessel stenosis, but also a stent with the same stenosis in it.
The presence of the stent on the balloon does not add any
additional dilating force or dilating capability in addition
to that of the balloon alone. The expanded intravascular
stent only maintains the degree of dilation that is achieved
acutely by the particular balloon. When a significant re-
sidual stenosis persists in the stent/vessel after a stent is
implanted with a usual “standard-pressure” balloon, the
original implanting balloon is replaced with a high-
pressure balloon and the dilation of the stent/vessel re-
peated. Very few (no!) residual stenoses do not respond
to a balloon dilation when a non-compliant, high-pressure
balloon is used for the reinflation and the balloon is
inflated to 20 to 25 atmospheres within a stent! This is true
particularly when the attempt at re-dilation is six, or more,
months after the original stent implant.
Pre-dilation of the area and the diameter of the pre-
dilation constitute a judgment decision during each stent
implant procedure. The decision is individualized in the
catheterization laboratory as the anatomy is visualized and
sized. When pre-dilation of the vessel is performed before
a stent implant, there is one major “rule” for the pre-dilation.
The pre-dilation of any stenotic lesion which precedes the

implant of an intravascular stent should be only to a dia-
meter that will accommodate the delivery sheath and which
is significantly smaller in diameter (at least 3 mm smaller in
diameter) than the diameter of the adjacent vessel or to the
diameter to which the stent is to be expanded at its initial
implant. In order to ensure fixation of the stent into some
residual, more rigid tissues in the vessel wall, pre-dilation
with a minimal diameter balloon ensures that the balloon
that is used for the delivery of the stent can be larger and
can expand the stent to a diameter which is definitely
larger than the pre-dilated (“softened”) stenotic area.
The pre-dilation is performed over the same Super-
Stiff™ wire over which the long sheath/dilator eventually
will be delivered. Once the wire is securely in place, a stand-
ard pressure dilation balloon is advanced over the wire to
the obstruction. The pre-dilation balloon used is only 2–
3 mm larger in diameter than the diameter of the stenosis in
the vessel and is at least 3 mm smaller than the adjacent ves-
sel, which should be the anticipated implant diameter of the
stent. The pre-dilation documents at least some “give” to
the stenosis in the vessel as well as opening the vessel to
accommodate the large sheath for the stent delivery. After
a pre-dilation is performed, the Super Stiff™ wire is main-
tained in its secure distal location, while the separate
balloon used for the pre-dilation is withdrawn, leaving
the wire in place across, and well beyond, the stenosis.
If a very tight area of stenosis cannot be pre-dilated at all
with a standard-pressure balloon, a high-pressure balloon
which is similar in size to the standard-pressure balloon is
used over the same wire in a repeat attempt to pre-dilate

the stenosis to the minimal diameter that will accommodate
the delivery sheath. Pre-dilation with the high-pressure,
but smaller, balloon ensures that if the standard, lower-
pressure balloon for the delivery of the stent does not fully
expand the area of stenosis, the area of stenosis will be
expanded to at least the diameter of the high-pressure,
pre-dilation balloon. This newly permitted increase in the
diameter provides sufficient evidence to be certain that
the implanting balloon can be removed from a partially
expanded (but secured) stent without displacing the stent.
Long indwelling sheath stent delivery technique
A long sheath/dilator set which will accommodate the
particular balloon/stent combination is advanced over
the pre-positioned Super Stiff™ wire and past the area of
stenosis which usually has not been pre-dilated. The tip
of the sheath is positioned at least several centimeters distal
to the area of obstruction in the vessel. The delivery of
the sheath to the lesion and securing the sheath in posi-
tion without creating kinks in the sheath, particularly
to branch pulmonary artery lesions, often is the most
difficult and challenging part of the entire procedure for
the implant of an intravascular stent. Once the sheath and
dilator are in position with the tip of the sheath well
beyond the lesion, the Super Stiff™ wire in the distal ves-
sel and the long sheath are fixed in place while the dilator
is slowly and carefully withdrawn over the wire and out
of the sheath. The sheath is allowed to bleed back from the
side port on the back-bleed valve until it is clear of all air
and possible clotsa remembering that the large, long
sheaths hold 10–15 ml of fluid (or air and/or clot!). Once

cleared by “passive drainage”, the sheath is flushed thor-
oughly by hand and then is attached to a continuous slow
flush to prevent the development of clots in the large
potential dead space within the sheath and around the
wire. After any pre-dilation is accomplished and as soon
CHAPTER 22 Intravascular stentsageneral information
563
as the delivery sheath is in position, if not administered
earlier, the patient is administered systemic heparin in a
dose of 100 mg/kilogram of body weight.
If a long sheath with an attached back-bleed valve/
flush port or a separate back-bleed valve/flush port
that which will accommodate the delivery catheter and
fit on the long sheath is not available in the particular
catheterization laboratory, the massive bleeding which
would occur from the open sheath can be prevented with
a “make-shift” solution. The bleeding through a non-
valved sheath with a wire within it is stopped effectively
(and temporarily) with a “rubber-shod” Kelly™ clamp
placed across the sheath (containing the wire) just outside
of the body where the sheath exits the skin. This prevents
the massive blood loss around the wire and through the
sheath after the dilator is removed from the sheath. Of
equal importance, it prevents air from being sucked into
the sheath during a deep inspiratory effort by the patient.
The clamp on the sheath does not allow any acute or
continuous flush of the sheath, and the clamp indents the
sheath, but only in an area outside of the body where the
clamp is applied. This indentation in the sheath does not
interfere with the passage through that segment of the

sheath that is outside of the body and can be straightened
manually, nor with the eventual delivery of the stent.
Of most importance, the “external” indentation does not
involve any areas that are in tight curves or bends in the
sheath in the course of the sheath to the target site.
When a separate, detachable back-bleed valve, which is
not built onto the sheath, is used for a stent delivery on a
large sheath with no built-in back-bleed valve, the balloon
alone is passed through the detached, separate back-bleed
valve and is slid back onto the shaft of the balloon dilation
catheter before the stent is mounted on the balloon. In this
way the stent mounted on the balloon does not have to be
forced through the smaller diameter lumen of the remov-
able, back-bleed valve. After the stent has been mounted
on the balloon, the stent/balloon unit is introduced com-
pletely into the non-valved sheath, the pre-mounted back-
bleed valve is advanced forward on the shaft of the
catheter onto the proximal hub of the sheath, and attached
to the hub. The clamp on the sheath is released, the sheath
is allowed to bleed back thoroughly through the side port
of the attached back-bleed valve, and then the side port is
attached to the flush system.
The exact stent and balloon that are used depend upon
the current, desired and eventual adult size of the vessel
and the location of the lesion in the vessel. For all vessels,
a stent always is used which eventually can be dilated to
the eventual adult diameter of the particular area of the
vessel. The length of the stent depends upon the length of
the actual lesion, the expected shrinkage in the length of
the stent with full expansion, the curvature of the vessel,

and the distances within the vessel before any branching
or bifurcations. The exact anatomy is defined angiograph-
ically or, when there is any question, by inflating the
“sizing” angioplasty balloon in the precise area at a very
low pressure.
In choosing the appropriate stent for a particular lesion,
the operator must always consider the amount of shrink-
age in the length of the stents with each increase in dia-
meter of the stents. This is particularly important with
the J & J™ Palmaz™ (Cordis Corp., Miami Lakes, FL) and
Genesis XD™ stents (Johnson & Johnson–Cordis Corp.,
Miami Lakes, FL), which shrink as much as 50% when
inflated to their largest diameters. Shrinkage in length to
some degree must be considered with almost all stents.
When a stent is to be expanded to 15 mm or larger in dia-
meter, in order to account for the shrinkage, the stent used
often must be longer in its collapsed state than the length
of the vessel where it is to be implanted. This shrinkage in
length makes it extremely important that the balloon and
stent are positioned precisely over the exact lesion at the
beginning of, and maintained in that position throughout,
the expansion of the stent during its implant. With a stent
properly and precisely placed on the delivery balloon,
the shrinkage usually, but not necessarily, is symmetrical
from both ends of the stent. As a consequence, most bal-
loon/stent inflations should be slow and observed very
carefully so that any asymmetric expansion or movement
in the position of the stent relative to the anatomy can be
adjusted before the stent is fully expanded and fixed
securely in an abnormal position. The expected shrinkage

of a stent occasionally is used to the operator’s advantage,
utilizing the further decrease in length with further
expansion of a stent to move the ends of the stent away
from crossing or branching vessels. The use of a BIB™ bal-
loon (NuMED Inc., Hopkinton, NY) is helpful in order to
allow some purposeful adjustment for an asymmetrical
inflation or shrinkage after the stent has been expanded to
only half of its final diameter.
The balloon is chosen specifically for the stent that is
being used and the diameters adjacent to the area of
implant while the exact stent is chosen for the particular
anatomy of the lesion as well as the diameters of the
immediately adjacent vessels. To prepare the balloon for
the stent, the balloon lumen is attached to the inflation
device and the balloon is inflated partially, but not to a
high pressure. The balloon is cleared of air by repeated
partial inflations/deflations while holding the balloon in
a vertical position with the tip of the balloon facing down.
Once the balloon is cleared of air, the balloon is deflated
slowly while simultaneously refolding the balloon manu-
ally around the shaft of the catheter. Once the balloon
is refolded as smoothly as possible, the balloon is main-
tained on “negative pressure” by withdrawing the
plunger of the inflation device and locking it in the
fully withdrawn position. The appearance of a continual
CHAPTER 22 Intravascular stentsageneral information
564
stream of tiny bubbles after applying negative pressure to
the balloon with an inflation device indicates a leak in the
balloon or the inflation system. The source of any leak is

identified and eliminated before proceeding, even if it
requires replacing the balloon or the inflation device.
There are some special preparations for the BIB™ bal-
loons. Each BIB™ balloon catheter has three lumens: one
lumen (with a blue hub) to the inner balloon, one lumen
(with a white hub) to the outer balloon, and a central
catheter lumen of the catheter itself (with a green hub).
In the original BIB™ balloons, where the central lumen
passed through the area of the balloons and before it
passed out through the tip of the catheter, the tubing of the
central lumen was very narrow and thin walled. This nar-
row tubing allowed the collapsed balloons to compress to
a diameter only slightly larger than the diameter of the
catheter shaft, but did not provide much longitudinal sup-
port in that area when there was no wire in this lumen. To
compensate for this during the preparation of the bal-
loons, each balloon catheter comes with a blunt, solid
metal, 0.035″ stylus. This metal stylus is inserted into the
distal end of the catheter lumen during balloon prepara-
tion and while the stent is being crimped on the balloon.
The stylus passes through the area of the balloon(s) and
back into the shaft of the catheter well proximal to the bal-
loons and, in this position, keeps that area of the catheter
and the balloons very straight and elongated.
For preparation of BIB™ balloons, both balloon lumens
are connected to manometered inflation devices. The
inner balloon is inflated and cleared of air and then
the outer balloon is inflated and cleared separately. Once
the balloons have been prepared, cleared of all air and
rewrapped around the catheter, the balloon lumens are

opened to neutral pressure and the stylus is removed. The
stent is passed over the refolded balloons, the stylus is
reinserted, and both balloons are again placed on negative
pressure. Since the stent over the balloons covers the
radio-opaque “markers” on the catheter within the bal-
loons, the BIB balloons with the stent mounted are viewed
under fluoroscopy in order to align the stent precisely and
evenly within the marks within the balloons. The stent
then is compressed (crimped) over the balloons by hand
exactly as with any other stent–balloon combination. The
stylus remains in the catheter during the “crimping” and
until just before introduction over the delivery wire.
Any balloons that have a Silicon™ or other “slippery”
coating also require “pre-preparation” before a stent is
mounted on them. The balloon is inflated until it is tense
and then the “slippery” coating is rubbed off the balloon
surface very vigorously with a dampened, 4 × 4 gauze
sponge. Once it is “rubbed clean” the balloon is manually
rewrapped over the catheter as it is deflated. When the
balloon has been cleared of air, the balloon is placed
on negative pressure and simultaneously is rotated and
“refolded” onto the shaft of the catheter in order to col-
lapse the balloon maximally onto the catheter shaft. Some
slight “irregularities” on the surface of refolded balloons
actually are desirable when using balloons for the deliv-
ery of stents. The irregular surface of the balloon helps to
keep the stent, which is hand-crimped on the balloon,
from sliding on the balloon during its passage through the
sheath. Before the stent is advanced over any balloon
for mounting on the balloon, the stent and surface of the

balloon are both coated with undiluted contrast solution.
As the contrast dries, it becomes very sticky and serves as
a “glue” that will help to hold the stent on the balloon.
To prepare the stent for mounting on the delivery bal-
loon, the entire length of the stent is dilated sufficiently to
allow the stent to pass easily over the balloon, and one end
of the stent is flared even wider by inserting the tip of a
large dilator (the dilator from the delivery sheath) into one
end of, and advancing it through the length of, the stent.
As the dilator is withdrawn from the end of the stent, the
dilator is angled slightly and rotated around within the
proximal tip of the stent, which, in turn, “flares” or makes
a “funnel-like” opening in one end of the stent. When
much larger delivery balloons are used, the entire stent
is dilated even further before introducing the stent by
gently advancing an even larger dilator into, and through,
the stent. The dilation and flaring of the stent facilitate
advancing the stent over the balloon and help to prevent
the ends of the stent from catching on the folds of the bal-
loon. With the Palmaz™ J & J™ stents, this is essential to
prevent the puncture of the balloon by a sharp tip at the
end of the stent.
With negative pressure applied to the balloon lumen,
the tip of the balloon catheter is introduced carefully into
the flared end of the stent and while the stent is allowed to
rotate slowly and very slightly (less than 360
°
) to corres-
pond to the direction of the folds of the balloon, the bal-
loon is advanced very gently into the stent. The catheter

and balloon always should slide freely into the stent. The
introduction of the stent over the balloon is performed
very gently and slowly to prevent a sharp tip at the end of
a stent from digging into, and puncturing, the balloon
during the mounting process. Particular care is necessary
with the J & J™ Palmaz™ stents (Johnson & Johnson,
Warren, NJ) which all have multiple sharp tips at each end.
If the stent catches on the balloon at all, the stent is with-
drawn, the balloon is re-formed or the stent dilated/flared
further. The stent is advanced over the balloon until it is
positioned over the exact center of the length of the balloon.
The stent is centered lengthwise as precisely as possible by
aligning the ends of the stent with, or equally between, the
metal markers on the shaft of the catheter beneath the bal-
loon material. When there is any question about the exact
positioning of the stent on the balloon, the stent/balloon
should be visualized under fluoroscopy.
CHAPTER 22 Intravascular stentsageneral information
565
Once the stent is centered exactly on the balloon, the
metal stylet of the BIB™ balloons is introduced into the
distal end of the catheter lumen of the balloon catheter
and pushed far enough into the distal end of the catheter
lumen of the balloon catheter to be entirely proximal to
the balloon. This stylet within the lumen supports the
lumen of the catheter during the subsequent forceful com-
pression of the stent over the balloon. Strong negative
pressure is maintained on the balloon lumen while the
connecting tubing and the inflator are inspected carefully
for any balloon leaks. A new puncture or leak is indicated

by a continual stream of small bubbles flowing into the
tubing or the inflator as the negative pressure is applied.
Once assured that there are no leaks, the stent is com-
pressed (crimped) uniformly on the balloon by manual
finger compression. There are no “crimping tools” avail-
able that are applicable universally for the large variety of
stents, balloon sizes, and balloon types or for the different
diameters of the catheter shafts of the different large
balloon dilation catheters used for the large variety of
congenital lesions. As a consequence, the crimping of all
non-pre-mounted stents is performed by hand. Several
more drops of contrast are placed on the surface of the
stent before the manual crimping on the balloon is started.
Starting with light finger pressure, finger pressure is
gradually increased while moving the fingers over the
entire length and around the circumference of the stent.
The circumference of the stent is squeezed onto the bal-
loon as the stent/balloon is rolled between the fingers.
Once the stent is relatively smooth and secure on the bal-
loon, then the fingers are squeezed as tightly as possible
and repeatedly over the entire surface of the stent/balloon
as the combination is rotated between the fingers. The
process is repeated using the tips of the fingernails to
compress the individual longitudinal struts forcefully
between the circumferential “bands” of the stent. This
fingernail compression creates a slightly irregular surface
on the mounted stent, which, in turn, helps to secure the
stent on the balloon, but does not affect the eventual stent
expansion or strength.
The short length of plastic tubing which is present over

the balloon in its sterile package is occasionally used as a
“smoothing” tool over the stent once it is mounted on the
balloon. When the stent has been compressed over the bal-
loon, the plastic tube is advanced over the combination
of the balloon/stent. The tube over the stent/balloon is
compressed manually between the fingers as tightly as
possible while the tube, stent, and balloon are rotated
between the fingers. However, this step usually is not nec-
essary and does not crimp the stent as tightly as direct
finger compression on the stent.
Once the stent is compressed securely on the balloon,
several more drops of undiluted contrast solution or albu-
min solution are spread on the surface of the balloon–stent
combination. The additional contrast is allowed to dry
briefly on the surface of the balloon–stent. This serves as
additional “glue” to help retain the stent on the balloon
and keep it from “sliding” on the balloon during delivery
through the sheath. The contrast “glue” works most effect-
ively if it is allowed to dry for 15–20 minutes.
Stent delivery over a wire and through a
pre-positioned sheath
The delivery of the stent/balloon combination to the
lesion, over a pre-positioned stiff wire and through a pre-
positioned long sheath, is the original and established
technique for the delivery of stents to the various congeni-
tal lesions. This technique is the most tested and reliable
technique available for the delivery of the current stents.
With the sheath and wire fixed in their position beyond
the area of obstruction, the balloon catheter with the
mounted stent is introduced over the proximal end of the

wire and advanced to the valve of the sheath. The intro-
duction of the balloon with the mounted stent into and
through the valved sheath depends on the length and type
of stent. The J & J™ Palmaz™ stents, which are longer
than 3 cm, can be pushed directly through the back-bleed
valve by gripping the most proximal end of the stent very
tightly with the tips of the fingers. As the proximal tip of
the stent is squeezed tightly and continuously in order
to maintain the stent in its exact position on the balloon,
the entire length of the stent is advanced through the
valve of the sheath, and the combination stent/balloon is
advanced into, and all of the way through, the attached
back-bleed valve chamber and into the sheath. There is a
small “flare” at the proximal end of the sheath within the
distal end of the back-bleed valve housing (chamber)
where the back-bleed apparatus is attached to the sheath
(Figure 22.7). This flare of the sheath creates a flange or
“ridge” within the back-bleed valve chamber between the
distal end of the valve housing and the proximal end of
the sheath within the valve “chamber”. This ridge is not
visible from outside of the back-bleed housing, but can
catch the distal end of the stent and block the passage of
the mounted stent from passing into the lumen of the
sheath from the back-bleed valve chamber. Longer stents
can be held securely at the proximal end of the stent with
the tips of the fingers and supported on the balloon as
the stent is advanced all of the way through the “valve” and
past this ridge.
The shorter P 108, 188, and 204 stents are too short to
maintain a grip with the fingers on the proximal end of the

stent as it is advanced all of the way through the back-
bleed valve and past the flange. When introducing the
shorter stents is attempted by just holding the stent with
the fingers, the stent is easily displaced proximally off
of the balloon as the proximal end of the stent passes
CHAPTER 22 Intravascular stentsageneral information
566
through the valve beyond the grasp of the fingers. This is
overcome by using the short “metal introducing tube”
supplied by J & J™ (Johnson & Johnson, Warren, NJ), or
a short, cut-off length of sheath as an introducing sleeve
(see Figure 22.1). The short length of “introducer” sheath
should be the same diameter as the delivery sheath, made
from a fairly stiff sheath material and approximately five
centimeters long. The proximal, cut, end of the short seg-
ment of sheath can be dilated with a forceps to flare the
end slightly. The balloon with the mounted stent is intro-
duced very carefully into the flared end of this sleeve until
the stent is completely within the sleeve. The sleeve along
with the contained balloon/stent are all held together and
are passed through the back-bleed valve and into the long
sheath until the sleeve seats on the flange between the
valve apparatus and the proximal end of the sheath (see
Figure 22.1). The balloon, stent, and catheter are advanced
out of the sleeve and into the shaft of the long sheath. The
sleeve is withdrawn out of the valve and back to the hub
on the shaft of the balloon catheter. The introduction of the
stent/balloon through the short sleeve can be used for the
P 308 stents, and may make their introduction through
the valve more secure. The short sleeve should definitely

be used with all of the open-cell stents (ev3, Plymouth, MN).
The pattern and the “looseness” of the cells of the open-
cell stents cause them to catch on the back-bleed valve
itself and cause the cells to pull apart if they are pushed
directly through a back-bleed valve.
When a long sheath with a separate and non-attached back-
bleed valve/flush port is the only long sheath available,
the balloon and the balloon catheter are passed through the
removable back-bleed valve/flush port separately before
the stent is mounted as described previously. The balloon
with the mounted stent is introduced into the open end of
the stent and the back-bleed valve, which is on the more
proximal shaft of the catheter, is pushed forward on the
shaft of the catheter and attached to the large sheath with
a continuous flush delivered to the pre-mounted back-
bleed valve. The remainder of the stent delivery then
becomes identical to the delivery through a long sheath
with a built-in attached back-bleed valve.
Once the proximal end of the stent/balloon combination
has been introduced and advanced several centimeters
beyond the valve and hub of the sheath, the balloon is
inflated very gently (~1 atmosphere) with the inflator and
the inflator is locked to maintain this pressure in the bal-
loon. This minimal pressure to the balloon expands the
exposed shoulders of the balloon, which extend beyond
each end of the stent, very slightly, without expanding the
stent at all. This is particularly useful when the balloon
is the same length or slightly longer than the stent. The
slightly expanded balloon and the “exposed” shoulders of
the balloon help to keep the stent from sliding proximally

on the balloon as it is advanced through the sheath. Unless
the balloon is inflated too vigorously, this still allows
the balloon to pass easily through the sheath. If the bal-
loon/stent does not move easily within the straight area of
the sheath, the balloon has been inflated with too much
pressure, and some of the pressure on the inflator should
be released. This slight inflation of the ends of the balloon
is important, particularly where there is a very tortuous
course of the delivery sheath through tight bends in the
vascular system.
While frequently observing the balloon/stent combina-
tion within the sheath as well as the position of the tip of
the wire and sheath and the course of the wire and sheath
on fluoroscopy, the balloon catheter with the mounted
stent is advanced over the wire within the sheath to the
involved narrowing in the vessel. As long as the wire and
sheath are maintained securely in place, advancing the
balloon and stent is usually accomplished quite easily. It is
important to repeatedly observe the entire course of the
sheath as well as the tip of the sheath and wire while the
catheter and the balloon/stent are being advanced within
the sheath. Occasionally, the “circumference” of a long
curve in the course of the sheath/wire as it passes through the
heart is widened as the balloon, stent, and catheter are
pushed against the outer circumference of any curve in
the sheath while it is passing through a dilated chamber or
vessel within the heart. As the balloon, stent, and catheter
push on and increase the curvature of the sheath, the dis-
tance along the wire from the skin entry site to the lesion
lengthens. If the increasing circumference of this curve in

the sheath/wire and, in turn, the actual length of the dis-
tance to the lesion are not noticed and not compensated for
by advancing the sheath and wire along with the catheter at
Figure 22.7 Flange (or flare) on proximal end of sheath within the back-
bleed valve chamber.
CHAPTER 22 Intravascular stentsageneral information
567
the skin, the tip of the sheath and the wire will be with-
drawn out of their secure positions distal to the lesion. As
soon as this “widening of the circumference” of the curve
begins to occur, instead of the sheath and wire remaining
firmly fixed outside of the body, the sheath and wire
outside of the body are advanced along with the bal-
loon/stent/catheter just enough to compensate for the
increased length being caused by the large curvature
within the heart.
Once the stent and balloon have been advanced
through the sheath to the area of the lesion, the stent
(on the balloon) is centered exactly at the area of maximal
narrowing. The slight pressure in the balloon lumen
is released and the balloon deflated completely before the
sheath is withdrawn off the stent/balloon. With the
stent/balloon still within the sheath and with the guide
wire still buried far out into the lung parenchyma, the
wire, catheter, and balloon/stent are fixed in this location
while the sheath alone is carefully withdrawn off the
balloon/stent/catheter/wire combination. This uncovers
the stent on the balloon over the wire centered in the
proper location in the area of narrowing.
After withdrawing the sheath, it is important to repeat a

selective angiogram through the separate venous catheter
either within, or just proximal to, the lesion in order to
verify the exact positioning of the stent in the stenosis.
Because of the stiffness of the wire, the catheter and the
sheath, often there is distortion of the vessel and a change
in the curvature and position of the wire/balloon/stent
combination relative to the stenosis or to relatively fixed
landmarks in the thorax after the sheath has been with-
drawn. This can displace the stent/balloon away from the
exact central area of stenosis compared to the location
before the wire was introduced. The repeat selective
angiocardiogram identifies any changes in relative posi-
tions and allows the stent/balloon to be readjusted into
the precise area of narrowing. Repositioning of the
stent/balloon/catheter in the area is similar to the reposi-
tioning of a balloon/catheter for angioplasty. The stent,
balloon, and catheter are advanced over the fixed wire to
advance the stent further into the lesion, but in order to
withdraw the stent/balloon/catheter, the wire alone is pushed
forward forcefully. As the wire advances, it pushes the
stent/balloon/catheter backwards while, at the same
time, keeping the wire forced forward into the distal loca-
tion in a very secure position.
During the passage of the balloon/stent/catheter
through the sheath, occasionally the stent slips on the bal-
loon and is displaced proximally on the balloon. If this
displacement is less than 1–2 mm and the stent is still
completely over the balloon, it usually is of little or no con-
sequence. However, the balloon and stent positions should
be inspected very carefully while the balloon and stent are

still within the sheath and before the sheath is withdrawn. If the
stent is displaced more proximally on the balloon, the stent
still may be in its proper position within the lesion, but the
distal end of the balloon, off of which the stent is displaced,
will be positioned further into the distal vessel and away
from the narrowing. A distal positioning of the balloon
usually results in the balloon/stent combination milking
backwards before the stent even begins to expand during
the initial balloon inflation. This results in the stent’s being
displaced and implanted in an improper location. If the
“extra distal balloon” extends into a small distal vessel
and the distally displaced balloon does not milk back out
of the vessel, the expansion of the balloon can result in
rupture of the small vessel.
If the stent is displaced more than 1–2 mm on the
balloon, and certainly if the stent extends completely off
the balloon at all while the stent and balloon are still
within the sheath, the implant procedure is abandoned
temporarily and the sheath is not withdrawn off the
balloon/stent combination. With the balloon/stent still
within the sheath and with the stent now positioned over
only the proximal end of the balloon, the balloon again is
inflated very slightly. This inflates only the distal end
of the balloon and creates a larger “shoulder” of balloon
distal to the stent. The entire catheter/balloon/stent is
withdrawn through the sheath, over the wire, and out of
the body. The larger “shoulder” of the balloon, which is
now completely distal to the displaced stent, helps to keep
the stent from sliding distally off the balloon as the combi-
nation is withdrawn through, and out of, the sheath. Even

with the “distal shoulder” on the balloon the stent often
catches at the valve of the sheath and is retained in the
valve chamber of the sheath after the balloon has been
withdrawn. Usually, the very end of the stent is visible
just within the valve and still over the wire. When the end
of the stent is visible just within the valve, a tip of the vis-
ible end of the stent is grasped with a small forceps and
pulled out through the valve.
If the stent cannot be retrieved from within the
sheath/valve, the entire sheath must be withdrawn over
the wire. Once the sheath is completely out of the body
and off the wire, the stent is pushed forward, through and
out of the distal end of the sheath with a dilator or balloon
catheter. Once the stent is retrieved from the withdrawn
sheath, the dilator is replaced in the sheath and the
sheath/dilator is re-advanced over the wire into the vessel
and to the lesion. If the sheath is damaged at all, a new
sheath/dilator set is used.
Unless it was damaged in the removal process, the
retrieved stent is re-mounted on the same or a new bal-
loon. When re-mounted, the stent is positioned 1–2 mm
forward (distally) of the center of the balloon. This leaves
the stent mounted slightly more distally on the balloon
with more “shoulder” exposed “behind” and more prox-
imal to the stent toward the shaft of the catheter. The
CHAPTER 22 Intravascular stentsageneral information
568
balloon catheter with the re-mounted stent is reintro-
duced over the wire, into and through the back-bleed
valve of the sheath, and advanced several centimeters into

the sheath. The balloon is again inflated minimally (with
approximately one atmosphere of pressure). The “for-
ward” positioning of the stent on the balloon allows more
of the proximal “shoulder” of the balloon to expand slightly
behind the stent, which, in turn, helps to prevent the stent
from sliding backward as the balloon/stent is advanced
through the sheath. Once the balloon/stent has been
advanced to the proper position as verified fluoroscopic-
ally, the balloon again is deflated before the sheath is
withdrawn off the balloon/stent.
Very rarely, as the sheath is being withdrawn off of
the stent/balloon, the stent again slides backward (prox-
imally) on the balloon along with the sheath or, inadvert-
ently, the stent/balloon is exposed with the stent already
displaced proximally on the balloon. In this circumstance,
after the sheath is completely off the stent but still partially
over the proximal balloon, the sheath is gently read-
vanced over the balloon. Usually, the edge of the distal
end of the sheath catches on the proximal end of the stent
and does not allow the stent to be withdrawn back into the
sheath. By continuing to advance the sheath forward very
gently, the stent can be pushed forward, and often can be
positioned back onto the proper location on the balloon!
This maneuver must be performed very gently and care-
fully with no excessive force. If the stent does not move
forward easily, it suggests that the sharp distal ends of the
stent struts are caught on the balloon. Any excessive force
applied to the sheath can push one of the sharp tips of the
end of the stent into the wall of the balloon and puncture
the balloon. This is a particular problem with the J & J™

Palmaz™ stents with the very sharp tips at both ends.
Fortunately, even the Palmaz™ stents and all of the other
stents can usually be re-advanced over the balloon quite
safely by using this maneuver with the tip of the sheath.
The sheath is withdrawn off the proximal end of the
balloon but no further. The sheath positioned in close
proximity to the balloon helps to support the shaft of the
balloon catheter during the implant. Once the stent is in
the exact, proper position in the stenosis and its correct
position on the balloon has been verified, the balloon is
inflated slowly to its maximum advertised pressure and
hopefully to the maximum diameter of the balloon.
During the inflation the stent is observed continuously
and recorded on biplane angiography or biplane stored
fluoroscopy. The inflation of the balloon expands the stent
into the stenosed area of the vessel to the diameter of the
implanting balloon. If there is even the suggestion of stent
displacement during the initial slow inflation, the in-
flation is stopped and the stent/balloon repositioned
correctly within the stenosis using manipulations of the
catheter, wire or sheath. Once the stent is expanded fully
or the balloon has reached its maximum pressure, the
balloon is deflated rapidly. Often, there is some waist or
incomplete expansion of the stent with the first inflation of
the balloon; however, with accurate prior sizing and posi-
tioning, the stent will be centered on the lesion and fixed
securely in the vessel. The deflated balloon is repositioned
over the wire very slightly forward or backward and the
inflation is repeated several times to achieve maximal
expansion of the entire length of the stent with the particu-

lar balloon.
After implanting the stent securely in the area of
stenosis and while the balloon is still within the stent, the
stent position and fixation are confirmed with a repeat
angiogram through the adjacent catheter. With the
balloon still positioned within the stent, the balloon is
reinflated at a low pressure. Then, simultaneously, as the
balloon is being deflated slowly and with the balloon still
within the stent, the long delivery sheath is re-advanced
gently and gradually over the balloon and into the stent as
the balloon deflates within the stent
10
. The inflated bal-
loon within the stent centers the proximal shaft of the bal-
loon catheter and the advancing edges of the tip of the sheath
within the lumen of the stent. This “centering” keeps the
edge of the distal end of the sheath from catching on the
proximal end of the stent as the sheath is reintroduced
into and through the stent. Often, as the sheath tip is
pushed against the balloon and as the balloon is deflating,
the balloon and the following tip of the sheath slide for-
ward together and through the stent before the balloon
deflates completely. This still accomplishes the goal of the
sheath advancing completely through the stent without
catching on, or dislodging, the stent.
Once the sheath is in or completely through the stent,
the balloon is deflated completely by applying negative
pressure to the balloon lumen. When the balloon has been
deflated completely, the negative pressure is released from
the inflating syringe. The balloon is withdrawn over the

wire and into the sheath with the balloon lumen on “neu-
tral” pressure while the balloon catheter is rotated very
slightly in the direction of the balloon folds (determined
earlier while preparing the balloon), and it is withdrawn
into the sheath. The release of the strong negative pressure
“softens” the folds or “wings” on the deflated balloon.
When the sheath can be repositioned and maintained in
its position through the stent, the sheath allows the balloon
to be withdrawn through the stent while the stent walls
are “protected” completely by the sheath from any rough
folds or “wings” on the deflated balloon as the balloon is
withdrawn. With the long sheath through the stent, a
catheter or a new, larger or different balloon can easily be
advanced reliably and safely through, or into, the newly
implanted stent without danger of dislodging the stent.
This balloon-assisted procedure for re-entering the stent
is extremely valuable in even the most straightforward
CHAPTER 22 Intravascular stentsageneral information
569
stent implant procedures but it is particularly important
when there are any curves in the vessel immediately prox-
imal to the area of the stent
10
. The greater the angle or cur-
vature of the vessel entering the stent, the more essential
the balloon-assisted re-entry technique becomes. The stiff
guide wire through the stent tends to “remain straight”
and to orient itself tangentially across a curved vessel (and
stent). This consistently forces the wire, catheter, and
sheath against one edge of the proximal end of the stent,

which, in turn, prevents even a finely tapered dilator
or catheter from entering the stent after its implant. The
balloon-assisted procedure for re-entering the stent with
the sheath is now the standard technique used after essen-
tially every stent implant.
Once the deflated balloon has been withdrawn from the
stent, preferably through the sheath with the wire and
sheath remaining through the stent, the balloon catheter is
withdrawn from the vessel and out of the body through
the sheath. The necessity for further dilation or for placing
additional stents is determined from pressure measure-
ments and repeat angiography while the sheath is still
passing through the stent. With the sheath in place within
the stent, any subsequent steps in the procedure are far
more straightforward. If a partially inflated stent is fixed
in the vessel and the vessel and stent are still stenotic, the
initial implanting balloon is replaced with a high-pressure
balloon to further expand the stent and vessel together.
Occasionally the sheath cannot be re-advanced into the
stent even over the actively “deflating” balloon, and on
withdrawal of the balloon through the stent, the balloon
catches on, and begins to dislodge, the stent. In this situ-
ation the sheath is re-advanced until the edge of the distal
end of the sheath purposefully is pushed against the proximal
end of the stent and purposefully caught against the stent.
The sheath that could not be advanced into the stent is
now caught on the end of the stent and is used to “but-
tress” the stent in its position in the vessel. With the sheath
fixed in this position against the stent, the stent is held in
place as the balloon is carefully withdrawn. Simultaneous

rotation of the balloon catheter facilitates the withdrawal of
the balloon out of the stent and into the sheath. It can be
helpful to advance the balloon beyond the stent, reinflate
the balloon at least partially, and then deflate the balloon
while rotating the balloon catheter to help “refold” the
balloon. Once refolded, the strong negative pressure is
released from the balloon before attempting to withdraw
the balloon from the stent.
If the sheath cannot be re-advanced into the stent while
the balloon is deflating within the stent, but the balloon
can be withdrawn out of the stent, the balloon is with-
drawn out of the stent, through the sheath and out of the
body. The long dilator is reintroduced into the sheath and
an attempt can be made at reintroducing the combined
sheath/dilator into and through the stent. Unfortunately,
even with an apparent tight and smooth fit of the tip of
the dilator over the wire and the tip of the sheath over the
dilator, the tip of the dilator or sheath often catches on the
proximal end of the stent and cannot be reintroduced into
the stent without dislodging the freshly implanted stent.
Occasionally the use of a new dilator, which is one size
larger than the sheath (particularly the 11- and 12-French
sheaths) and with a different curve formed on the tip of the
dilator, will facilitate the sheath and dilator re-entering
the stent. Advancing or slightly withdrawing the wire
separately while simultaneously advancing the sheath/
dilator, occasionally changes the angle of the wire as it
enters the stent enough to allow the tip of the dilator
and subsequently the sheath to enter the stent. However,
remarkably, the very tiny interspace between the wire and

dilator or sheath and dilator frequently is very effective at
catching on the sharp, exposed end of the stent and totally
prevents reintroduction of the sheath into the stent. This
problem provides the rationale behind the reintroduction
of the sheath into the stent over the initial balloon as it is
being deflated within the stent whenever it is possible.
When the balloon cannot be withdrawn into the sheath
once it has been withdrawn out of the stent, both the bal-
loon and sheath are withdrawn from the body over the
wire with the wire still fixed securely through the stent into the
vessel far distal to the lesion. Even when the balloon cannot
be completely withdrawn into the sheath, at least the par-
tially refolded, proximal “shoulder” of the balloon usu-
ally can be withdrawn into the distal end of the sheath,
which, in turn, “covers” the rough folds in the shoulder at
the proximal end of the balloon and partially protects the
vein and tissues as the combination sheath and balloon
are withdrawn. This partial covering of the shoulder of
the balloon allows the partially folded balloon to be with-
drawn through the vein puncture site, subcutaneous
tissues, and skin without causing significant vessel/tissue
damage. Again, it is important to release any negative pres-
sure from the collapsed balloon in order to “soften” the
exposed folded edges or “wings” on the balloon.
Once the balloon and large sheath are out of the body
and off the exchange wire, either a new long sheath or a
new short sheath/dilator of the same diameter as the pre-
vious long sheath is introduced over the wire, into the
vein. The new, large sheath prevents bleeding and is less
traumatic to the vein for any subsequent catheter or bal-

loon introductions. In the past, large balloons for subse-
quent or further dilations were introduced into the vein
directly over the stiff exchange wire without a sheath.
However, this is no longer recommended. The rough
walls of a large “folded balloon” passing directly into
the tissues and particularly on withdrawal from the ves-
sel/tissues are significantly more traumatic to the vessel
than a larger diameter, but fixed, indwelling and im-
mobile sheath.
CHAPTER 22 Intravascular stentsageneral information
570
The larger balloons used for re-dilation of a stent,
particularly the 15 and 18 mm balloons, are prepped
“negatively” or at most, minimally inflated during their
preparation before their introduction in order to prevent
the development of the large “wings” or rough irregular
shoulders from a previously fully inflated/deflated
balloon. When introduced through a short sheath and
advanced over the wire without a long sheath passing
through the stent, the balloon must be advanced very
carefully into and through the stent. Even though the
proximal end of the stent is wide open, because of the tend-
ency of the Super Stiff™ exchange wire to “straighten”,
the wire usually presses against one edge at the end of the
stent and the tip of the balloon, or the folds of the balloon
almost always catch on the ends of the proximal wires of
the stent. Again, slight, alternating traction with pushing
or advancing the wire as the balloon is advanced, often
changes the angle and relative positions of the wire/bal-
loon/catheter as the tip of the balloon enters the stent. In

particular, as traction is applied to the wire, the wire often
is pulled away from the wall of the stent. This allows the
tip of the balloon to enter the stent first and then the entire
balloon to pass into and through the stent. This traction on
the wire must be performed very cautiously since any
traction on the wire also can withdraw the tip of the wire
from its secure position in the distal pulmonary artery!
As a last alternative, partial inflation of the balloon with
the balloon tip positioned just proximal to the stent may
be enough to move the wire away from the edge of the
stent and “center” the tip of the balloon catheter in the ves-
sel/stent. As the balloon is deflated slowly, the tip of the
balloon catheter and, hopefully, the balloon itself can be
advanced into the stent over the “centered” wire. This
inflation of the balloon is used as a last resort since the
inflation eliminates the original smoother “factory fold”
of the balloon and may make the introduction of the rest of
the balloon into the stent impossible.
Occasionally, no maneuver allows the reintroduction of
a sheath, catheter, or balloon back into a freshly implanted
stent without some movement of the stent. If a stent
moves at all in its freshly implanted state, it can easily be
displaced! Even if the position of the implanted stent does
not “look or measure” perfectly, if the freshly implanted
stent moves even slightly with subsequent manipulations,
reintroduction of anything back into it should be aban-
doned at that time. When the stent has been in place for
three to six months, it becomes fixed very securely into the
vessel wall and can safely be re-entered and re-dilated
during a subsequent catheterization.

Once the re-dilation balloon has been introduced into
the stent by whichever method is successful, the larger
or high-pressure balloon is centered exactly within the
stent and inflated to its maximum pressure or diameter
to expand the stent to its final diameter. The inflation/
deflation is repeated several times to ensure maximum
expansion of the stent in the previously stenosed area.
After maximum inflation of the balloon within the stent,
the balloon is deflated completely with maximum negat-
ive pressure. The negative pressure is released from the
balloon lumen before withdrawing the balloon from
the stent. If a long sheath was used with the re-dilation
balloon, if possible the sheath is re-advanced into and
through the stent as the balloon is deflating, as described
previously.
With all dilation and stent implant procedures, the follow-
up pressure measurements and selective angiograms
in the proximal vessel are performed before the deflated
balloon is withdrawn from the stent. This allows further
reinflation to correct for residual hemodynamic problems
or abnormalities seen on the angiogram or for the reintro-
duction of the sheath into the stent. Once satisfied with the
repeat hemodynamics and the anatomic appearance, the
balloon is withdrawn carefully out of the stent and into
the sheath or more proximal vessel and from there, out of
the body. When the balloon has been removed from the
body, an end-hole catheter is passed over the wire, and, if
possible, to a position distal to the stent. If it is not possible
to get it through the stent, the catheter is positioned just
proximal to the stent. The Super Stiff™ exchange wire is

withdrawn carefully through the catheter, out of the stent,
and out of the body.
“Front-loading” stent delivery
The “front-loading” stent delivery technique was devel-
oped because of repeated problems with hand-mounted
stents sliding proximally off the balloons while they were
being advanced through long delivery sheaths
11
. Front-
loading of the stent eliminates this problem. In addition,
with the “front-loading” technique, a delivery sheath one,
or even two, French sizes smaller can often be used for the
delivery of a comparably sized stent/balloon. For the
front-loading technique, an end-hole catheter and then a
Super Stiff™ guide wire are positioned exactly as for the
standard long sheath stent delivery. The same extra effort
is used to position the catheter tip and, subsequently, the
distal end of the wire, as securely and as far distally to the
stenosis in the vessel to be stented as possible.
Technique for front-loading
The stent and balloon are prepared very differently for the
“front-loaded” delivery. The long sheath that is used for
front-loaded stent delivery is chosen so that the balloon
with the stent mounted can just barely be accommodated
within the sheath. This permits the use of a long sheath
that is at least one, if not two, French sizes smaller than the
long sheath that is used for a standard, through-the-sheath
CHAPTER 22 Intravascular stentsageneral information
571
delivery of the same balloon/stent. While outside of the

body, the delivery balloon is passed from the proximal to
the distal end and completely through the long sheath
until the balloon is exposed entirely beyond the distal end
of the sheath. The stent is mounted on the balloon while
the balloon extends out of the distal end of the sheath, but
otherwise, the stent is mounted exactly as for the stand-
ard, through-the-sheath delivery technique.
Once the stent is mounted and tightly crimped on the
balloon, the balloon catheter with the mounted stent is with-
drawn into the distal end of the sheath. The withdrawal into
a tight fitting sheath requires considerable “finger com-
pression” of the tip of each individual exposed strut at the
proximal end of the stent as each strut is withdrawn into
the sheath. The balloon, stent, and catheter are withdrawn
into the distal end of the sheath until the entire stent
(on the balloon) is within the distal tip of the sheath, but at
the same time, the tip and the “shoulder” of the balloon,
which are distal to the stent, extend just beyond the distal
tip of the sheath. The balloon is inflated very slightly.
Since most of the balloon and all of the stent are within the
very tight fitting sheath, the inflation only expands the
exposed distal “shoulder” of the balloon, which extends
just outside of the tip of the sheath. In this position, the
inflated distal tip of the balloon extending out of the tip
of the sheath forms a “dilator tip” for the sheath while
the “inflated” portion of the balloon, which is within the
sheath, helps to “fix” the relative positions of the balloon
and stent tightly against the inner diameter of the sheath.
While religiously maintaining the distal position of the
previously positioned long wire, the original short sheath

used for the diagnostic catheterization and the positioning
of the delivery wire is removed over the wire. The tract
into the vein is dilated to at least the diameter of the long
sheath containing the balloon/stent. While the balloon
catheter and the long sheath are fixed together very tightly
by finger compression over the balloon/stent at the distal
end of the sheath and the balloon catheter and stent at the
proximal end of the sheath, the combination of the balloon
catheter with the stent mounted on the balloon, which is
positioned just within the tip of the long sheath, and the
long sheath all are advanced as one unit, over the wire,
and introduced through the skin subcutaneous tissues
and into the vessel. The partially inflated balloon extend-
ing beyond the tip of the sheath acts as the “dilator tip”,
although it does not have as smooth an interface with the
sheath or as stiff a “dilating” tip as a regular dilator. The
balloon catheter within the sheath does not provide as
rigid support for the shaft of the sheath as the standard
long dilator provides. Once through the skin and into
the vessel, the combination balloon/catheter/sheath is
advanced together as one unit over the wire, through the
heart and to the lesion. Very careful attention and a very
tight grip on the sheath along with the enclosed shaft of
the catheter are necessary to keep the balloon/stent/
sheath combination all fixed together in precisely the same
relationship while the combination is advanced through
the vascular system and heart. The introduction and
advancing of this combination requires at least two pairs
of “knowledgeable” hands! It is impossible for a single
catheterizing physician to advance the sheath while at the

same time keeping the catheter and sheath fixed together
as one unit and maintaining the wire securely in place.
The hands of the additional and knowledgeable operator
or assistant maintain the wire in position and the sheath
and catheter fixed together while the primary operator
advances the sheath/catheter combination. This is the
most difficult part of a “front-loaded” stent delivery.
In addition to the difficulties in introducing the com-
bination sheath/balloon/catheter/stent over the wire
and through the skin and subcutaneous tissues, the
front-loading delivery technique has several other very
significant problems, which occur while the combination
is being advanced through the heart to the lesion. These
problems are significant enough to prevent the technique
from being used more regularly. The inflated tip of the
balloon extending out of the tip of the sheath does not cre-
ate a smooth “dilator” tip nor a smooth interface between
the surface of the balloon and the “lip” of the distal end of
the sheath. Often, when there are any curves in the course
to the lesion, a wide gap is created in this interface. As the
sheath/catheter/stent combination is advanced, the gap
or “lip” at the leading edge of the tip of the sheath may
catch on intravascular or intracardiac structures and pre-
vent the sheath from advancing further.
The inflated balloon within the distal end of the sheath
does not fix the balloon–sheath relationship together very
securely and, as a consequence, the balloon/stent/sheath
combination functions very poorly as a “single unit”. As
the combination balloon/stent/sheath is advanced over
the wire and through the heart, the balloon with the

mounted stent is very easily pushed out of the sheath.
Inadvertent displacement of the balloon/stent out of the
sheath opens the stent partially and precludes any further
advancing of the sheath or stent. If the stent on the balloon
advances out of the sheath completely, it easily becomes
entrapped in the intracardiac structures. Conversely, the
sheath can be pushed forward over the stent/balloon, which,
effectively, pushes the stent/balloon back into the sheath.
When the stent/balloon/catheter is further back in the
sheath and the tip of the balloon is away from the tip of the
sheath, the balloon tip no longer extends beyond the tip of
the sheath as the “dilator”, and the open tip of the sheath
without any “dilator” creates a very blunt and sharp
“leading edge”, which prohibits the sheath from being
advanced any further.
When the balloon is inflated to a significantly higher
pressure in order to prevent balloon/stent movement
CHAPTER 22 Intravascular stentsageneral information
572
within the sheath, the lumen of the balloon catheter as it
passes through the balloon is compressed by the pressure in
the balloon and, in turn, prohibits the movement of the
combined balloon/stent/sheath over the wire.
Finally, the shaft of the balloon catheter within the
sheath does not provide the stiffness and support for
“pushing” the sheath compared to the true long dilator.
As a consequence, this lack of “shaft” support of the
sheath results in kinks in the sheath, buckling of the
sheath, or even “accordioning” of the sheath on itself
when the sheath is advanced against any resistance. This

precludes advancing the sheath any further and can result
in the stent/balloon being extruded out of the sheath
prematurely as the catheter alone is advanced beyond a
stuck sheath which “shrinks” in length as it accordions.
The multiple disadvantages of the front-loading technique
outweigh most advantages over the standard long sheath
delivery technique. The front-loading technique is used
only when the standard delivery technique through a pre-
positioned long sheath has failed several times.
When a front-loaded stent can be advanced all of the
way to the stenotic area, and as soon as the stent is cen-
tered in the lesion, the balloon, which is partially inflated
within the sheath, is deflated completely. After the balloon
is deflated, this “loosens” the balloon/stent within the
sheath and removes any inflating pressure from the bal-
loon. With the balloon deflated, the sheath is withdrawn
off the balloon/stent. The remainder of the implant of the
stent is exactly as with the delivery technique through a
pre-positioned long sheath.
“Ing” technique of front-loading
To overcome the “interface” problems between the tip of
the partially inflated balloon and the tip of the sheath,
Dr Frank Ing further refined the front-loading technique so
that a tip segment of the long dilator which came with the
long delivery sheath that is used to deliver the stent/bal-
loon, is used as the “dilator” during the sheath delivery
12
.
This modification of the front-loading technique and
equipment eliminates the problems of the discrepancy

of the “balloon shoulder/tip of sheath” interface. This
modification also allows P 108 or P 188 stents to be
mounted on even smaller balloons and delivered through
sheaths as small as 6- or 7-French! This, in turn, allows the
implant of stents which eventually can be expanded to the
final large adult diameters into the central vessels of infants
and small children. The smaller sheaths used with this
modified technique follow the stiff wire to the lesion with-
out kinking better than the larger diameter sheaths. The
shaft of the balloon catheter still does not create as much
support for the sheath as does the long dilator which
comes with the sheath and, as a consequence, extreme
care must be used in order not to bend or kink the sheath
as the combination smaller sheath/balloon catheter is
advanced through curves or bends within the cardiac
structures.
The “Ing” modified, front-loaded device is advanced to
the lesion over a pre-positioned Super Stiff™ wire which
must still be positioned far distal to the lesion with the
same care and attention used for the standard long sheath
delivery technique. The stent mounting and the prepara-
tion of the balloon catheter and sheath require more
individual preparation by the operator than the more
“standard” front-loading technique.
The long dilator is removed from the long sheath that is
to be used for the front-loaded delivery of the stent. Like
the “standard” front-loading procedure, the balloon
catheter first is advanced from the proximal to the distal
end and through the long sheath so that the entire balloon
is outside of the distal end of the sheath. The distal end of

the long dilator is amputated 2–3 cm proximal to the tip of
the dilator. The lumen of the dilator at the proximal end
of this cut-off segment of the dilator is significantly larger
than the “wire” lumen, which is at the very distal tip of the
dilator. By rotating the proximal end of the shaft of this cut-
off segment of dilator in the “jet” of heat from an electric
“heat gun”, the proximal end of the cut-off segment of
dilator is softened. While the proximal end of the segment
of dilator is still soft, the lumen of the softened proximal
end of the segment of dilator is forced over the distal tip of
the balloon catheter that is to be used for the delivery of
the stent. As the lumen of the amputated tip of the dilator
is forced over the tip of the balloon catheter, it is twisted or
“screwed” slightly onto the tip of the catheter distal to the
balloon. While the portion of the dilator is still “soft”, an
umbilical tape is tied tightly around the proximal portion of
the cut-off tip of the dilator, which is now positioned over
the very distal tip of the balloon catheter. As the segment
of dilator cools with the tie around it, the wall of the cut-
off segment of dilator shrinks with a circumferential
“groove” in it created by the tie around it. The combina-
tion of the shrinking as it cools and the groove within the
segment of dilator which is over the tip of the balloon
catheter, forms a tight bond between the amputated dila-
tor tip and the tip of the balloon catheter. This process
fixes the proximal end of the cut-off tip of the dilator
against the distal shoulder of the balloon. The dilator tip
now, essentially is a part of the balloon catheter.
The stent is mounted on the balloon similarly to the pre-
viously described “front-loading”. The stent is centered

on the balloon, making sure that the distal end of the stent
is behind the proximal end of the attached segment of the
cut-off tip of the dilator. The balloon, stent, and catheter,
with the attached tip of the dilator, are withdrawn into
the sheath until the proximal, straight portion of the newly
attached segment of the tip of the dilator is withdrawn
just within the tip of the sheath. The withdrawal of the
CHAPTER 22 Intravascular stentsageneral information
573
balloon/stent into the sheath requires the same individual
crimping maneuvers over the tips of the struts of the stent
as it is withdrawn into the distal tip of the small sheath.
Only the tip of the dilator, which is attached to the tip of
the balloon catheter, should extend out of the sheath. This
tip of the original dilator for the long sheath re-creates
the original, smooth interface between the sheath and the
“dilator”. The balloon is inflated partially within the
sheath to help secure the balloon/stent/catheter within
the sheath at that position. With the balloon and stent
front-loaded they are delivered over the pre-positioned
stiff delivery wire exactly as with the previously described
front-load technique.
Even with the “Ing” modification, it still is somewhat
difficult to maintain the front-loaded balloon/stent pre-
cisely together with the sheath as the combination is
advanced through the heart, and the shaft of the balloon
catheter still does not provide as strong support for the
advancing sheath as the true long dilator. The biggest dis-
advantage to this technique, however, is that the “special
tips” for the balloon catheters must be “hand-made” and

“hand-mounted”, which requires some talent and con-
siderable additional time on the part of the operator dur-
ing each case.
“Sheath-within-a-sheath” technique for the
delivery of stentsccombined front-loading and
pre-positioned long sheath delivery technique
The final sheath technique for stent delivery is a combina-
tion of the standard pre-positioned long sheath delivery
and a front-loading delivery technique. It is used in very
extenuating circumstances where a large stent must be
delivered through an extremely dilated heart or a very
tortuous course within the heart, and particularly to
lesions in the pulmonary arteries. The “sheath-within-a-
sheath” technique usually is not used unless one or all of
the previous long sheath techniques have failed. The
sheath-within-a-sheath technique is particularly useful
when there is a recurrent problem of the stent being dis-
placed off the delivery balloon as it is advanced to the
lesion through a long sheath. An end-hole catheter and a
Super Stiff™ exchange guide wire (Medi-Tech, Boston
Scientific, Natick, MA) are pre-positioned across the lesion
and well into the vessel distal to the lesion as is accom-
plished with all of the other stent delivery techniques.
With the sheath-within-a-sheath technique, the stent is
front-loaded into the smallest diameter long sheath that
will accommodate the desired stent when it is mounted
on the delivery balloon. The front-loaded stent, balloon,
and sheath, in turn, are delivered to the lesion through
another, still larger diameter, pre-positioned, long sheath.
This second, larger diameter sheath/dilator set must be

six to seven centimeters shorter than the smaller long sheath
into which the stent/balloon is front loaded and must be
large enough in its internal diameter to accommodate the outer
diameter of the smaller diameter long sheath in which the
balloon/stent is front-loaded. The outer extra-large long
sheath is usually two French sizes larger than the long
inner sheath. The second, larger diameter, long sheath/
dilator set is advanced over the pre-positioned Super
Stiff™ wire and well past the lesion in the vessel. The di-
lator is removed from the extra-large sheath while main-
taining the Super Stiff™ wire in its secure distal location.
With this extra-large sheath in place, the dilator removed
over the wire, and the sheath cleared of all air and clot, the
smaller diameter long sheath with the previously front-
loaded balloon/stent/catheter is introduced into the
proximal end of the pre-positioned, larger diameter long
sheath. The front-loaded balloon/stent/catheter/sheath
is advanced to the lesion through the larger long sheath. The
front-loaded inner sheath/catheter prevents the stent
from sliding on the balloon while it is being advanced
through the outer sheath, while the outer larger sheath
provides a smooth course through the heart for the front-
loaded balloon/sheath tip interface and obviates most of
the problems of the pure front-loaded delivery. The inner
sheath/balloon catheter combination provides some addi-
tional support for the outer sheath to prevent kinking of
either sheath. This technique has always been successful
when the other techniques have failed. The major disad-
vantages of the sheath-within-a-sheath technique are the
extra equipment necessary and the necessity of using the

even larger diameter outer sheath.
Non-sheath delivery of stents
The delivery of stents which are currently available and
suitable for central vessels in congenital heart lesions has
been attempted without a long covering sheath, but with-
out consistent or reliable results. Stents that are not pre-
mounted on balloons by the manufacturers cannot be
fixed securely on the balloons. In addition, the J & J
Palmaz™ stents (Johnson & Johnson, Warren, NJ) have
exposed, rigid ends, which protrude off the surface of
the balloon when the balloon/stent passes through any
curve. These tips of these stents frequently catch on intra-
cardiac structures and can easily be pushed off the balloons
as the stent/balloon combination is advanced through
any curves in the vascular course to the lesion, especially
through the intracardiac structures. Once the stent has
slipped off the balloon, the loose stent on the catheter shaft
has sharp exposed ends. When the catheter/balloon with
the loose hand-mounted stent is moved either forward
or backward, the stent can catch on intravascular struc-
tures and make removal difficult and dangerous to the
patient.
CHAPTER 22 Intravascular stentsageneral information
574
The Medium and “Large” Genesis™ stents (Johnson &
Johnson–Cordis Corp., Miami Lakes, FL) are pre-mounted
commercially and can be delivered safely without a sheath.
The walls of the balloons actually are “incorporated” into
the mesh of the stents and fix the balloon on the stent very
securely until the balloon is expanded. Unfortunately,

these pre-mounted Genesis™ stents are only available on
balloons up to 9 mm in diameter, and the stents can be
expanded further only to a maximum diameter of 10–11 mm.
Although they are commercially available in the United
States as well as the rest of the world, they are not
applicable for use in any central vessels in humans except
possibly under very extenuating, life-threatening situ-
ations. Although these stents are much easier to deliver, the
stents themselves create a future iatrogenic stenosis in
any vessel which eventually and normally will grow to a
diameter greater than 11–12 mm! The stenosis created by a
limited diameter of a stent unequivocally will require surgery
on the stent/vessel for relief of the iatrogenic stenosis.
Larger, prototype Genesis XD™ stents (Johnson &
Johnson–Cordis Corp., Miami Lakes, FL) applicable
for use in central vessels were developed and produced
pre-mounted for experimental in vivo studies, and were
tested successfully in animals
13
. These prototype stents
are flexible and have closed cells at the ends producing a
smoother end to the stent. Like the smaller diameter ver-
sions, these larger Genesis XD™ stents were “embedded”
very firmly on the balloons and could be delivered
through all varieties of tortuous vasculature without a
sheath and without dislodging the stent. Unfortunately,
these pre-mounted, larger stents would be primarily for
congenital heart patients and, as a consequence, the
“small market” for these apparently does not “justify” the
commercial investment to produce them. If the larger

Genesis XD™ stents ( Johnson & Johnson–Cordis Corp.,
Miami Lakes, FL) were made available pre-mounted,
these stents would obviate almost all of the difficulties
of stent delivery and make the implant of intravascular
stents in pediatric and congenital heart patients easier for
the operators and infinitely safer for the patients.
Special circumstances for stents
Dilation of rigid stents to large diameters
As discussed earlier in this chapterain the discussions of
large balloonsa when balloon expandable intravascular
stents are expanded on standard dilation balloons, the
ends of the balloons inflate first causing the ends of the
stents to flare out before the center of the stents even
begins to expand. With large rigid stents, the flared ends
of the stent create an acute angle off the long axis of the
stent and vessel (see Figure 22.3). The ends of the stent, in
turn, project toward and into the walls of the vessel. The
flaring of both ends of the rigid stent also creates an angle
at the center of the stent between the two flaring ends.
With an initial expansion up to 10–12 mm in diameter,
neither the angle of the distal tips against the walls of the
vessel at the end of the stent nor the central angle appears
to be of any consequence. However, with initial expansion
to larger diameters than 12 mm, the flared, distal ends
of the stent become almost perpendicular to the walls of
the vessel. When the ends of the stent are sharp, they dig
into, and create a ring of small, punctate circumferential
“perforations” in, the vessel walls before the center of the
stent begins to expand. As the center of the stent begins
to expand, these embedded tips of the stent are pushed

linearly along the vessel wall creating small linear tears at
each puncture site. In vessels surrounded by dense scar
tissue this probably is of no consequence, but in a “native”
vessel these tears can be through the media and even
through the adventitia.
With the initial expansion of rigid stents to diameters
greater than 12 mm, the angle created at the center of the
stent also becomes significant (see Figure 22.5). When the
angle at the center of the stent becomes more acute than
90°, it very likely cannot be “re-straightened” as the stent is
expanded to its full diameter and, in turn, leaves a “kink”
or “waist” in the expanded stent as further pressure
against that area pushes against a perpendicular ridge of
struts at the center of the stent (see Figure 22.5).
Because of this phenomenon, when rigid stents are
implanted with initial diameters greater than 12 mm, they
are expanded sequentially, starting with a balloon less
than 10 mm in diameter. This is achieved in the case of
smaller vessels or very tight stenoses by beginning the
implant with a single, smaller, delivery balloon. In the
larger diameter vessels/stenoses, the initial implant is
performed using a Balloon In Balloon™ (BIB™) balloon
(NuMED Inc., Hopkinton, NY), which allows sequential
expansion and still allows fixation in a large vessel with a
larger diameter stenosis.
When a stent initially implanted at a very small dia-
meter, or when a residual small central “waist” is being
re-dilated to a larger diameter, the re-dilation is performed
incrementally with separate balloons which are increased
sequentially in diameter. If there is a central waist in a

stent which is 10 mm or less in diameter, a full, further
expansion up to 15 or 18 mm expands the ends of the stent
first and aggravates the central “waist”, possibly creating
a kink in the center of the stent and making it impossible
to dilate it completely.
Bifurcating stents
The primary indication for bifurcating stents is the pres-
ence of stenosis at, or very close to, the branch point or
CHAPTER 22 Intravascular stentsageneral information
575
bifurcation of two or more significant vessels. If a single
Palmaz™ P _ _ 8 or P _ _ 10 series stent (Johnson &
Johnson, Warren, NJ) is placed across the bifurcation or
branch, the flow to the vessel usually is not blocked, but
the physical access to the branching vessel will be blocked
(“jailed”) by the initial stent crossing the non-stented
branch, which, in turn, will eliminate any subsequent
access to that branch with a catheter. Branch or bifurcating
vessels of any significance are stented with the branching
or bifurcating stents implanted simultaneously with the
stent in the main vessel. Occasionally the orifice of the
bifurcating or adjacent branch vessel is wide open, but the
distal branches in that same vessel have significant steno-
sis which will need intervention either immediately or in
the future. In that situation, the proximal, non-stenosed
branch must be protected with a stent implanted simul-
taneously and “bifurcating” with the primarily stented
vessel to “protect” the access into the non-stenosed more
proximal branch vessel.
The implant of large stents in areas of bifurcation or

at the origin of large branch vessels, particularly in the
pulmonary arteries, is technically the most challenging
procedure performed by the pediatric interventional car-
diologist. First, it involves the implant of two (or more)
stents simultaneously along with the use of three (or
more) simultaneous venous catheters. The exact location
of the stenosis and the relation of the stenosis to the branch
or bifurcation must be defined very precisely. The two
(or more) stents must be implanted simultaneously and
very precisely into their exact locations. Unless very precise
implant techniques are used, the simultaneously implanted
and bifurcating stents can easily create a catastrophic
situation. When simultaneous stents are to be implanted,
both branches are analyzed very carefully for the degree
of stenosis, the distance from the bifurcation to the steno-
sis, and the distance to any additional branch points.
When implanting bifurcating stents simultaneously, it
is even more important to use balloons slightly shorter
than the stents which are being implanted. Longer bal-
loons flare (“dumbbell”) the ends of each stent during
early inflations much more than balloons that are slightly
shorter than the stent. Flaring of the ends of the stents cre-
ates the perpendicular radius of sharp tips of the struts at
the ends of the stents, particularly with the rigid, J & J™
Palmaz™ stents. When adjacent stents are implanted
simultaneously, these exposed extended sharp ends of the
struts very likely will puncture the adjacent balloon,
which is expanding the second expanding stent.
When crossing stents are implanted, both stents should
be at least 3 cm long and the crossing points of the two

stents should be at, or as close to, the center of each of the
stents as possible. At the same time, the proximal open
ends of both stents must be proximal enough in the more
proximal vessel to allow access and not be obstructed by
the side of the adjacent (crossing) stent (Figure 22.8).
If there is a relatively long area of stenosis in either of
the vessels, the more proximal areas which include the
crossing points of the stents, are addressed with the initial
implant of the stents. Although two stents implanted
simultaneously tend to support and fix each other in
place, each separate stent should be appropriate for the
size of the separate branch vessel in which it is implanted
and be capable of fixing securely into the walls of that
vessel on its own.
Occasionally, one of the stents in a bifurcating or cross-
ing situation can be implanted without inflating and
expanding the second balloon and stent simultaneously.
However, access to the branching vessel, in which the stent
is not being implanted (expanded) initially and simultan-
eously, must be “protected” before and during the implant
of the first stent in the other branch. This “protection” of
the branch is achieved by delivering the wire and the
sheath/dilator to the other branch vessel before the first
stent is implanted. The sheath/dilator is left in place in the
side branch vessel during the entire implant of the initial
stent in the first vessel.
Figure 22.8 Crossing stents implanted in a bifurcating lesion: (a) stents implanted too far distallyAproximal ends of implanted stents overlap each other,
obstructing subsequent access into at least one of the bifurcating/branch vessels; (b) bifurcating stents implanted more proximally with stents “crossing” each
other nearer their centers. Proximal ends of stents extend into more central vessel and provide subsequent access to both branches.
CHAPTER 22 Intravascular stentsageneral information

576
This separate implant of the stents has the advantage
that there is no simultaneously inflated stent to puncture
the adjacent balloon during the inflation for the implant of
at least the first stent. At the same time, when the second
stent is implanted in a position crossing or next to the pre-
viously implanted stent, the balloon in the first stent must be
inflated along with and during the expansion of the balloon
in the second vessel/stent in order to prevent the initial
stent from being crushed. The expanded balloon within
the stent which is already implanted and expanded, helps
to “protect” the second balloon from the sharp ends of the
struts of the original stent and helps to prevent puncture
of the adjacent (second) balloon by these sharp tips of the
original stent. The technique of implanting crossing or
bifurcating stents one at a time has the disadvantage of
not creating the support against the tissues provided by
the two expanded stents adjacent to (crossing) each other
when they are implanted into large vessels. This is particu-
larly true when one of the adjacent, more proximal orifices
is not stenotic.
When there is a bifurcation stenosis occurring distally
in association with an additional and contiguous more prox-
imal single stenosis in the main, feeding vessel (Figure 22.9),
management of the combined lesions with the implant of
intravascular stents becomes more complex. Although it
is counterintuitive to implant a stent in the more prox-
imal vessel and then have to work through the freshly
implanted stent to implant more distal stents, the single
more proximal stenosis, in fact, must be addressed first before

the additional bifurcating stents are placed in the more
distal branching areas of stenosis!
To overcome these problems, the larger single stent,
which will be in the more central stenosis that is prox-
imal to the bifurcating stenosis, is implanted first
(Figure 22.10). Once the more central stent is secured, the
more distal branching stenotic vessels are cannulated
simultaneously through the more proximal stent with
two (or more) catheters and wires passed separately but
adjacent to each other through the proximal stent. The
two or more stents in the branching vessel are implanted
with the proximal ends of the bifurcating stents both im-
planted and overlapping within the distal end of the more
proximal single stent (Figure 22.11).
When the more proximal stent is very secure, the distal
bifurcation stenoses can be addressed immediately after
the more proximal stent is implanted. However, if there is
a question about the stability of the first stent, the distal
branch stenoses are addressed at a subsequent catheter-
ization. Once the bifurcating stents are in place, any sub-
sequent dilation, of the single more proximal stent and/or
either one or both of the distal stents, must be performed
with the number of balloons equal to the number of the
more peripheral, distal stents. These balloons are always
inflated simultaneously with the proximal ends extending
back into the single proximal stent and the distal ends
extending out of the proximal stent into each of the
branching stents/vessels.
If two (or more), distal side-by-side or bifurcating stents
are implanted first, in order to dilate and also support the

more proximal single vessel stenosis with “a stent” after
the two distal stents have already been implanted, two
side-by-side stents would have to be implanted in the more
proximal single vessel stenosis in order not to crush one of
Figure 22.9 Diagram of combined central proximal right pulmonary artery
stenosis along with distal bifurcating right branch pulmonary artery stenosis.
Figure 22.10 Single large stent implanted first in the single, more central
stenosis, which is proximal to the bifurcating stenosis in the same vessel.
Figure 22.11 Distal bifurcating stents implanted through (out of) and in
tandem with the single more proximal stent.
CHAPTER 22 Intravascular stentsageneral information
577
the more distal stents! This would create (and necessit-
ates) a dual channel in the single vessel. The dual channel
would have to extend as far proximally as any more prox-
imal stenosis in order to treat the stenosis with implanted
stents (Figure 22.12).
When there are dual stents and/or two stent orifices
adjacent to each other anywhere in a vessel which requires
dilating and/or the implant of an additional stent, sepa-
rate balloons must be inflated simultaneously in each of the
adjacent stents during any subsequent dilation of either of
these stents. This of course holds true as well if there are
more than two adjacent stents (e.g. in a trifurcating branch
stenosis!). Any dilation more proximal (with or without
stents) made with a single balloon that is adjacent to and
outside of a stent which is not being supported by a sec-
ond balloon in that stent, will crush the adjacent stent
that is not supported with an inflated balloon in it at the
bifurcation or where the stents are next to each other (Fig-

ure 22.13). Any balloon and/or catheter in the adjacent
but unprotected stent/vessel could be trapped outside of
the expanding new stent!
When a single, more central stent is implanted in a
lesion that is very short and immediately proximal to the
bifurcation stenoses, occasionally a “skirt technique”a
which was originally described for coronary lesionsais
used to implant the initial, proximal stent
14
. In order to
ensure dilation and support with a stent of the short more
proximal stenosis as well as to guarantee access to both
branches of the distal bifurcation, and in order not to over-
dilate either of the distal branches while implanting the
single, much larger, more proximal stent, the proximal
stent is mounted on, delivered over, and implanted on two
separate, adjacent balloons within the single proximal stent. A
stent is chosen that will expand the proximal vessel/
stenosis to the desired diameter. Then, the two smaller
balloons, which together will expand the single stent
enough to fill and open the proximal pulmonary artery
to the desired diameter, are chosen and “negatively
prepped”. The two balloons are placed side by side within
the single stent and the stent is compressed and crimped
tightly over the two balloons. A single, larger diameter long
sheath is used that will accommodate the combined dia-
meter of the two balloons together with the single stent
mounted over them. The large, long, sheath/dilator set is
introduced and advanced over a Super Stiff™ wire which
is positioned as far distally as possible into one of the

stenotic branches. The tip of the long sheath is positioned
distally in the stenosis in the proximal vessel where this
initial stent, which will be delivered on the two balloons,
will be implanted. The large, long sheath is advanced as far
distally as possible over the dilator/wire within the single
proximal vessel and just to the area of the bifurcation
stenosis off the central vessel. The long dilator and Super
Stiff™ wire are removed, leaving the sheath in place.
A small torque-controlled end-hole catheter, through
which the wire which will be used in one of the balloon
catheters on which the stent is mounted will pass, is intro-
duced into and advanced through the large, long sheath.
From the tip of the long sheath, the catheter is manipu-
lated into and far distally in one of the stenotic bifurca-
tion branches off the more central artery. Once the first
catheter is securely in place, a second similar catheter is
advanced through the long sheath adjacent to the first
catheter, manipulated and advanced distally into the other
stenotic branch of the bifurcation. Two separate exchange
length wires, which the two balloons on which the stent is
mounted will accommodate, are advanced through the
separate catheters and wedged into the respective separ-
ate distal pulmonary artery branches. The two catheters
are withdrawn over the separate wires and the two bal-
loons which are compressed within the single stent are
introduced over the two side-by-side wires, into the large
long sheath and advanced as a single unit over the two
wires and through the long sheath to the stenotic area of
the more proximal pulmonary artery.
It is imperative that the two separate end-hole catheters

and, in turn, the two separate wires are advanced initially
to the separate stenotic pulmonary artery bifurcating
branches through the single long sheath which was posi-
tioned initially in the more proximal pulmonary artery.
This ensures that the two catheters, and in turn, the two
Figure 22.13 “Unprotected” stent in an adjacent vessel crushed by balloon
expanded in adjacent vessel.
Figure 22.12 Parallel tandem stents extended back into single proximal
channel.
CHAPTER 22 Intravascular stentsageneral information
578
wires are passing through the exact same course through
the heart and do not deviate separately around even a
single chorda!
As the stent and two balloons are advanced distally
from the tip of the sheath, which is positioned in the prox-
imal pulmonary artery, the tips of the two balloons, which
extend out of the single stent, follow the separate wires
into the separate bifurcating branches off the more central
single pulmonary artery. By pushing the balloons/stent
forward as far as possible, the single stent becomes posi-
tioned immediately adjacent to the bifurcation, while at
the same time buttressed against, and straddling the two
branches equally. The sheath is withdrawn proximally off
the two balloons/single stent, and with the wires and bal-
loon catheters pushed forward as firmly as possible, the
two balloons are inflated simultaneously. This expands
the single stent into the proximal vessel with the distal end
of the stent “flared” like a “bi-legged skirt” toward the
two distal stenotic branches. Any subsequent dilations or

stent implants in the proximal vessel or the branches are
performed with separately delivered, but simultaneously
inflated, balloons.
Tandem stents
Tandem stents are frequently necessary in vessel stenoses
that are longer than the available stents or in curved
lesions in order to have the straight rigid stents conform
better to the contour of the vessel. The use of tandem
stents is particularly important with the limited available
lengths and the lack of flexibility of the J & J™ Palmaz™
stents (Johnson & Johnson, Warren, NJ).
In the deployment of tandem stents, it is important that
no gap is left (or allowed to occur later) between adjacent
stents. Alternatively, the adjacent ends of two stents that
are within the same vessel, should have a wide separation
between the approximated ends of the abutting stents at
the time of implant. The exposed, rigid and sharp end of a
single stent, by itself, creates an irritation, which results in
a build-up of the intima. The irritation of the vessel wall
between the apposing ends of two stents that are in close
approximation to each other, is aggravated by the move-
ment or bending of the vessel that occurs in the gap
between the two stents. The vessel movement causes the
two apposing, sharp ends to “grind” the tissues between
them, resulting in very aggressive, localized, intimal pro-
liferation. Intimal proliferation in these “gap” areas is one
of the few documented causes of significant re-stenosis
in the many pediatric/congenital lesions that have been
stented.
At implant, the adjacent tandem stents are overlapped

by a minimum of 35 to 70%. The degree of overlap depends
upon the type of stent, the expected implant diameter
of the stents, which effects the shrinkage in length of the
stents, and the age and expected growth of the patient and,
in turn, the future growth in length of the vessel. When
P _ _ 8 stents are implanted in potentially large (15–18 mm
diameter) vessels, which, however, are small in diameter
at the time of implant, they are overlapped at least
60–70%. This degree of overlap is necessary to prevent
separation of the stents as the stents shrink in length as
they expand and to allow for subsequent growth of the
vessel in length. P _ _ 8 stents shrink ~50% in length with
expansion to their largest diameters. The newer ITI™
stents (ev3, Plymouth, MN) shrink minimally in length
when expanded sequentially and do not require as much
overlap to allow for the initial shrinkage or for shrinkage
later with further dilation.
When tandem stents of all types are implanted in small,
but growing patients, the potential growth of the patient
and length of the vessel must be taken into account and an
even greater overlap of the stents created at the time of
implant. None of the stents “elongate” after implant, and,
in fact, when stents are dilated further in diameter to
accommodate the growth of a vessel, most stents shrink
even further in length with re-dilation! At the same time,
the tissues elongate as well as increase in diameter with
growth, which results in the adjacent, tandem stents,
which have a fixed length and are fixed in the tissues of the
wall of the vessel, separating from each other, even when
there was a significant overlap at the time of implant.

When there is insufficient overlap of the adjacent stents,
the ends actually separate and create an area of extreme
irritation and intimal proliferation between the ends of
the stents. As a consequence, when sufficient overlap of
adjacent tandem stents cannot be provided to allow for
the patient’s growth, it is better to leave a large gap of at
least 5–6 mm between the ends of the adjacent stents at the
time of the initial implant. An additional stent can be
implanted between the original stents after several years,
when the patient is re-catheterized and the original stents
are re-dilated.
When the area of stenosis to be stented is in a curved
vessel, two, or more, overlapping, short rigid stents
should be implanted in tandem around the curve, rather
than one long, straight, rigid stent. This is particularly
important with the J & J™ Palmaz™ stents. A shorter stent
on a short balloon is easier to deliver and implant in a
curved vessel and a series of overlapping, tandem, short
stents conforms better to the curvature of the vessel than a
single long stent. A longer straight, rigid stent implanted
in a curved vessel not only does not conform to the curva-
ture of the vessel, but leaves the long, sharp ends of a rigid
stent digging into the outer circumference of the curva-
ture of the vessel wall at an acute angle. The sharp ends of
the stents implanted at an acute angle to the wall of a ves-
sel are another demonstrated cause of excessive intimal
proliferation and re-stenosis following stent implant in
CHAPTER 22 Intravascular stentsageneral information
579
congenital lesions with the longer J & J™ stents (Johnson

& Johnson, Warren, NJ).
If multiple tandem stents are anticipated, at the initial
implant of each of the earlier stents, the earlier stents
implanted are not expanded to their final maximum
diameter with their implant, but with their initial expan-
sion are expanded only enough to fix the stents in place.
This smaller initial diameter of the earlier stents allows
several more millimeters of expansion with the implant of
each subsequent stent. This, in turn, allows subsequent
stents to be implanted at a slightly larger diameter than
the original stents in order to ensure the fixation of each
additional stent as it is expanded into the same vessel. The
stents which were implanted earlier and initially, are
expanded further and incrementally with the implant
of each additional stent. Eventually the full diameter of
that particular vessel can be achieved after the entire
length of the tandem stents has been implanted, yet with-
out significant over-dilation of the particular vessel when
the initial stents have been implanted at smaller than final
diameters. If, on the other hand, the first or earlier stents
are expanded to the full diameter of the vessel with their
implant, in order to “over-expand” the subsequent stents,
they must be expanded to a diameter slightly larger than
the vessel to secure the additional stent(s) in the vessel and
within the initial stents.
When tandem stents are implanted in veins, the most
distal (in the direction of blood flow) stent is implanted first.
If the proximal (in the direction of blood flow) stent is
implanted first, stasis of blood flow occurs in the newly
created lumen within the stent (proximal in the flow to the

more distal stenosis). This blood, which is not flowing,
tends to clot before the more distal stents are implanted
and more adequate flow can be established through them.
In the pulmonary arteries with pulsatile, more vigorous
flow, the opposite occurs. The more proximal stent is
implanted first. If the more distal area is opened with no
blood flow coming from the more proximal, still stenotic
vessel, the blood in the dilated pulmonary bed distal to the
obstruction stops and will thrombose.
Recent developments in stents
There are some improvements in the stents and in
the delivery systems for peripheral vascular use, which
somewhat inadvertently have “trickled down” or been
modified for the pediatric and congenital arena. Of the
hundreds of new stent designs and stent materials that
have been introduced in the past decade for use in adult
vascular diseases, several have applicability, although not
“approval”, for the pediatric and congenital population.
The three “groups” of relatively new or “pending” stents
which already have promise for congenital lesions are the
Cheatham-Platinum™ (C-P™) stents (NuMED Inc., Hop-
kinton, NY), the Mega™ and Maxi™ stents (Intra Thera-
peutics Inc., St Paul, MN) and the Genesis XD™ stents
( Johnson & Johnson–Cordis Corp., Miami Lakes, FL). All
of these have been discussed in some detail earlier in this
chapter.
The Cheatham-Platinum (C-P™) stent (NuMED Inc.,
Hopkinton, NY) has had extensive use world wide (except
in the United States) for the standard congenital lesions.
It is not available routinely in the United States. It was the

first stent available in the much larger diameters, which
also had some flexibility and had rounded ends for safe
use in larger lesions. Because of its unique characteristics
and wide range of “available” and “custom” sizes, and its
availability with an expandable “covering”, the C-P™
stent has had some unique investigational and compas-
sionate use applications throughout the world, including
even in the US. The most innovative of these uses is the
“re-building” or “creation” of “internal venous tunnels”
with very large, long and covered C-P™ stents for the
“completion of the Fontan” in the catheterization labora-
tory. This catheterization procedure, if perfected, could
replace two major cardiac surgical procedures.
The Double Strut™ stent (Intra Therapeutics Inc.,
St Paul, MN) was the first stent approved for “human use”
in the US which had both flexibility and a truly open-cell
design, which have considerable appeal for use in con-
genital lesions. Several newer stents from ITI™ are now
approved for human use in the US and appear to be even
more suitable for pediatric and congenital lesions. The
Mega™ and Maxi™ stents (ev3, Plymouth, MN) still have
the favorable open-cell design as the Double Strut™ stent
but are stronger and/or larger.
The Genesis XD™ stent (Johnson & Johnson–Cordis
Corp., Miami Lakes, FL) is an apparent replacement (suc-
cessor) for the Palmaz™ P _ _ 8 series of stents (Johnson
& Johnson–Cordis Corp., Miami Lakes, FL). The Genesis
XD™ has some flexibility, smoother ends and a partially
flexible design, all of which improves the ease and safety
of its use. Even with the improvements in its design, the

Genesis XD™ appears to have retained the strength of the
P _ _ 8 stents. The Genesis XD™ stent appears to fulfill
most of the criteria of an ideal stent for many of the central
congenital heart vascular stenoses, although more clinical
experience with it is necessary before too much compla-
cency develops about the delivery of stents!
Stenting of the atrial septum
Standard intravascular stents are occasionally used to
maintain an opening in the atrial septum for the tempor-
ary, or sometimes even permanent, palliation of complex
congenital heart defects. Often the septal openings created
CHAPTER 22 Intravascular stentsageneral information
580
by a balloon atrial septostomy (Chapters 13) or a blade
and balloon atrial septostomy (Chapter 14) spontaneously
shrink in diameter or even close completely. Standard
intravascular stents can be placed in the atrial openings
to maintain their patency. Stents with a restricted central
diameter are used to create openings, but with a restricted
flow in atrial baffles in “failed Fontan” patients. These uses
of intravascular stents are covered in detail in Chapter 14.
“Future” developments in intravascular
stents
Large flexible stents without sharp tips at the
ends
It should be possible with a few adjustments of the laser
cutter to produce an even larger version of the Genesis
XD™ stent comparable in size and strength to the Palmaz
P 4010 and P 5010 stents ( Johnson & Johnson–Cordis
Corp., Miami Lakes, FL). A larger stent with the smoother

ends and with the slight flexibility of the Genesis XD™
would improve the safety of the stents for use in the aorta
or any other very large vessel. The smoother ends alone
probably would eliminate the aneurysms that develop
during the implant of stents in the aorta as a result of the
sharp tips of the rigid J & J™ stents. Whether the pedi-
atric/congenital “market” is large or important enough
for the manufacturers to make this happen, still remains
to be seen. Hopefully, the already available Maxi™ stent
(ev3, Plymouth, MN) will fulfill the same criteria or the
large C-P™ stents (NuMED Inc., Hopkinton, NY) will
become available in the US to provide this added safety
for these patients.
Pre-mounted, flexible stents
A prototype, pre-mounted version of the Genesis XD™
stent (Johnson & Johnson–Cordis Corp., Miami Lakes, FL)
was mentioned earlier. This pre-mounted stent under-
went in vivo animal tests in early 2001
13
. The pre-mounting
of these stents, like the other Genesis™ stents, is unique,
with the stent almost “incorporated” into the surface of the
balloon. This pre-mounting along with the “smoother”
ends of these stents allowed the Genesis XD™ stents to be
delivered safely without the protection of a long sheath,
even when passing through the right heart and through
very tortuous vessels, and without the stent catching on
intravascular structures or being dislodged from the bal-
loon. This very secure type of pre-mounting requires a
great deal of collaboration between the manufacturers of

both balloons and stents.
The commercial availability of the larger pre-mounted
intravascular stents would make the implant of stents for
all of the pediatric and congenital heart patients easier
and infinitely safer. At the same time, pre-mounted
stents initially would increase the cost of the procedure
significantly. When stents that are not pre-mounted are
used, a single stent is suitable for use in many different
lesions and vessels with many different diameters. The
separate stent merely is mounted on the particular dia-
meter balloon, which is applicable to the particular lesion.
For the most part, the balloons that are used to implant
the intravascular stents are already in the inventory of
the catheterization laboratory for the balloon dilation of
vessels and valves. However, when using pre-mounted
stents, an inventory of a full range of each size of the pre-
mounted stent/balloon combination would be necessary
and the balloons with the pre-mounted stents would not
be useable for other angioplasties without stent implant.
Eventually, the costs of the procedures would “even out”,
with less time required for the preparation and delivery
procedure for the stents, less loss of balloons and stents
from stent slippage or balloon rupture/entrapment, and
certainly less time used as a consequence of the signi-
ficantly worse complications now encountered with some
of the “hand-mounted” stents.
Unfortunately, the major (and almost only!) applica-
tions for the larger pre-mounted stents are for pediatric/
congenital heart lesions. As such and in the environment of
the US FDA, which does not recognize any stent for pedi-

atric or congenital heart use, this population does not
represent a market, much less a profitable market, and
certainly not an area for future development, for Johnson
& Johnson–Cordis™ or, so far, for any other stent manu-
facturers to pursue specifically for this use.
Covered stents
There is considerable interest and ongoing development
of “covered stents” for the exclusion of aortic aneurysms
in atherosclerotic adults. Covered stents have been used
occasionally on a compassionate basis for emergency
“bail-out” in a few unique pediatric/congenital patients.
The early covered stents that were used in congenital
patients were hand-made by wrapping a “sleeve” of
fabric or freshly harvested vein over or around a non-
expanded stent. The sleeve of covering material had the
same diameter as the desired final diameter of the vessel
that was being stented. The sleeve of fabric or tissue was
attached to the stent by several sutures and the stent with
the covering sleeve was mounted on a balloon. The com-
bination was compressed and delivered through a sheath
similar to the delivery of other balloon-expandable stents.
These hand-made stents required a significantly larger
introductory sheath than the stent/balloon alone. When
the stent expands, the covering sleeve expands and/or
unravels and creates an “impervious” channel in the area
CHAPTER 22 Intravascular stentsageneral information
581
which is “covered” by the sleeve. Hand fabrication of
these covered stents was tedious and very time consum-
ing and, of equal or more importance, the end product

was very unpredictable and imprecise.
Eventually, new modifications with the covering
material built into, or onto, the stents were developed
and a variety of covered stents now are manufactured
and are available commercially for the adult market.
(Manufacturers include: WALLGRAFT-Medi-Tech, Boston
Scientific, Natick, MA; JoStent-Jomed Implantate, GMH,
Rangendingen, Germany; Zenith-Cook Inc., Blooming-
ton, IN and Excluder-W. L. Gore & Associates, Flagstaff,
AZ). These covered stents are for adult vascular use and
for use predominantly outside of the US. Simultaneously,
more needs are arising for covered stents in congenital
heart lesions.
Covered stents for use in congenital patients have even
more stringent limitations than standard stents. Besides
the lack of availability for congenital use, the major prob-
lem for the use of covered stents in many congenital
patients is the subsequent growth of the patients and ves-
sels. There is one oral communication which suggests that
some expandable polytetrafluoroethylene (ePTFE) cov-
ered stents can be dilated further in order to accommod-
ate the growth of a patient even several years after their
implant. Until the single observation can be duplicated
and demonstrated to be reproducible in further animal or
human trials, this observation cannot be taken for granted
for all patients and types of stents/coverings. Certainly, a
non-stretchable “covering” or fabric material over a stent,
which is similar to a circumferential prosthetic conduit,
cannot expand beyond the manufactured maximum
diameter of the material, particularly after there has been

tissue ingrowth into the covering/fabric. This type of cov-
ered stent, in turn, would create a fixed maximum diameter
for that vessel, which is fixed by the diameter of the cover-
ing of the stent at the time of implant. Until new mater-
ials/designs are available that can definitely be dilated
further once the covered stent has been in place for many
months, covered stents should be used only in patients
who have reached adult size, or in extremely extenuating,
life-threatening, circumstances.
The covered stents which have been or currently are
being used in pediatric/congenital lesions, are those
which are available for adult peripheral vascular lesions
and, for the most part, have been used in isolated, “emerg-
ency bail-out” situations. The first uses of covered stents
were for the control of acute tears in vessels. Originally,
these were tears in smaller vessels (coronary arteries),
and usually the tears were iatrogenic following balloon
dilations. Subsequently, the same concept was used for
the occlusion of degenerative tears and aneurysms of
the aorta. There are at present extensive developments
and multiple clinical trials for the treatment of aortic
aneurysms in adults with covered stents. With favorable
outcome of these trials and newer developments in the
covered stents, covered stents eventually will be more
applicable to, and more readily available for, congenital
lesions.
There already has been a sporadic use of covered stents
in pediatric/congenital heart lesions for the repair of
acute tears in vessels, which occurred during balloon dila-
tion procedures. This currently involves the problem

of the necessary individual, “hand” preparation of the
covered stent during such an emergencyawhich is time-
consuming and somewhat inconsistent. The humanitar-
ian approval or off-label availability of a commercially
manufactured, more sophisticated covered stent in mul-
tiple sizes would make this application more effective,
more consistent and, again, much safer and even life-
saving in acute catastrophic emergencies. Covered stents
also have an application for the occlusion of “window
type” systemic to pulmonary communications, particu-
larly those arising from the ascending aorta or entering
into difficult to reach locations in the more distal pul-
monary arteries (e.g. unusual ductus and/or Potts
descending aorta to left pulmonary artery shunts)
15,16
.
However, if a covered stent is used for this purpose in
much smaller patients, the covered stent must be capable
of further dilation to accommodate for the patient’s
growth! A few hand-made covered stents have been used
under extenuating or emergency circumstances in con-
genital patients for the purposeful occlusion for managing
iatrogenic tears in vessels following balloon dilation of
branch pulmonary arteries.
Covered stents have been used for the treatment of aor-
tic tears that occur during the dilation of coarctations of
the aorta, or even are suggested for use in the routine
stenting of coarctation of the aorta
17
. A long covered stent

potentially obliterates the vasa-vasorum, intercostals
and/or the spinal artery in the areas which can be included
under the stent and covered by the stent, with the possibil-
ity of causing tissue ischemia or even paraplegia. In the
adult atherosclerotic, dissected aorta, where covered
stents are being used extensively, these critical side/
branch vessels in general have not created a problem.
Additionally, there is a real incidence of stent displace-
ment during stent implants for coarctations of the aorta.
Usually the errant stent is “re-implanted” in a smaller
distal area of the aorta, and with a non-covered stent and
the knowledge that flow is preserved through the side of the
open stent, there is little concern when the stent crosses
side branches. However, a covered stent which becomes
displaced in the aorta, potentially would occlude critical
side branches which it crossed! In addition, there is the
necessity of very large introductory sheaths for hand-
made and commercially available covered stents which
are currently available for the aorta.
CHAPTER 22 Intravascular stentsageneral information
582
In spite of the lack of prospective or planned commer-
cial development in this area, the most innovative uses
of covered stents to date have been in congenital heart
lesions. Covered stents were used to “rebuild” intra-atrial,
venous channels which were disrupted and leaking
significantly in several complex patients with single
ventricles who had undergone “Fontan” cavopulmonary
type single ventricle repairs
18

. There now are proposed,
surgical/interventionist (“hybrid”) collaborative trials
for the use of covered stents to “complete a Fontan” proced-
ures prospectively. These developmental uses of covered
stents are described in more detail in Chapter 32.
“Open-ring” stents
The use of intravascular stents in the central and poten-
tially large vessels still represents a problem in very young
or very small patients who have a very significant poten-
tial for further growth. Small diameter, pre-mounted stents,
which can be delivered easily to the pulmonary arteries or
to other sites in very small infants, are readily available,
however, these small diameter stents cannot be dilated sub-
sequently to a size adequate to the diameter of even a small
adult central vessel. Any stent with a small or limited
diameter, which cannot eventually be dilated to the adult
diameter of the vessel, represents an iatrogenic stenosis and
should not be used in these vessels. This problem has been
overcome partially by the “Ing” modified, front-loading
delivery technique, which was described earlier in this
chapter and which allows the delivery of the current,
shorter, P 108 and P 188 stents through as small as 7-
French sheaths. These particular shorter stents can be
dilated to adult diameters; however, this is not the perfect
solution. Even these stents and the necessary sheaths/
dilators are large and rigid relative to the size of a very
small infant. Another area of potential future stent develop-
ment is a small stent, which either dissolves or can be
opened later to allow dilation to a diameter beyond the
nominal diameter of the original stent in order to allow

dilation of the particular vessel to the eventual diameter
of the adult vessel.
Dr Ing developed a simple but very innovative “open-
ring” stent and validated its usefulness in one animal
study
19
. With his technique, one or two longitudinal cuts
were made along the entire length of standard P 154 or P
204 stents (Johnson & Johnson, Warren, NJ), which have a
maximal diameter of 10–11 mm. This created a small stent,
which was split and “opened” longitudinally, completely
along one side, or with two longitudinal cuts on the oppo-
site sides of the stent, a “bi-valved” stent. The incised
halves of the stent were reattached to each other with two
or three 6-0 resorbable sutures, which were placed along
each cut edge. These “reattached” small diameter stents
were mounted on a balloon, delivered and implanted
easily through a 6-French sheath exactly as any other very
small stent. These small, potentially “open” stents were
then dilated acutely up to 11 mm in diameter during their
implant without disruption of the sutures holding the two
halves together. The resorbable sutures fixed the two lon-
gitudinal halves of the stent together securely enough to
allow dilation to the full diameter of the particular stents.
The expanded, sutured stent, when implanted, supported
the dilated vessels at the widest diameter of the implanted
stents, while the sutures maintained the edges of the
stents together securely and long enough to allow secure
fixation of the stents into the tissues and to provide ad-
equate support of the dilated vessel. The sutures resorbed

over 8 to 12 weeks. Any time thereafter, further dilation of
the vessel in the area of the stents separated the previously
incised and sutured, longitudinal cut(s) in the stents,
allowing further dilation well beyond the nominal limits
of the original standard, smaller diameter stents. This
unrestricted dilation of the “opened” stents in the vessel is
sufficient to compensate for any subsequent growth of the
vessel. The “open-ring” stent allows the delivery of a very
small stent to very small central vessels in young infants
as small as 3–4 kilograms, while the “opened” stent sub-
sequently allows the vessel to be dilated eventually to an
adult diameter as the small stent splits.
The stents which were utilized in the animal investiga-
tion were prepared specifically for the study by the
manufacturer (Johnson & Johnson, Warren, NJ). The
manufacturer performed the longitudinal cuts in the
stents and polished and coated the cut edges in order
to resist corrosion similar to the surfaces and ends of all
stents. Unfortunately, the very small number of patients
who would require these stents prohibits a prospective
human study which could reach enough statistical
significance to satisfy the FDA, even if it lasted a century.
As a consequence, these professionally cut and polished
stents are no longer produced for any use. The only cur-
rent alternative for the “Ing” open-ring stent is to “hand-
cut” the stents, which would leave the edges rough and
not coated and, in turn, create some added unknowns for
a clinical trial. Hand cutting in order to individually pro-
duce the “open-ring” stents also increases the difficulty
and consistency of preparing each stent, and certainly

would decreases the safety of their use in these precarious
positions in these already critically ill infants.
Recently, the “open-ring” concept has reappeared in
Europe as the “Growth Stent”
20
. The growth stent is laser
cut and electro polished as a “bi-valved” stent with
specific, facing, “tongue and grove” areas where the two
longitudinal halves fit together in order to maintain the
edges together more securely (QualiMed, Winsen/Luhe,
Germany). The edges are held together with the same
resorbable sutures used by Dr Ing and are completely re-
absorbed after 8 weeks. In addition to its small size, this
CHAPTER 22 Intravascular stentsageneral information
583
stent has the advantages of having some open side cells
and “Omega” hinges between adjacent rows of cells, which
together give the stents considerable flexibility. The great-
est advantage is that it is professionally manufactured and
commercially available at least outside of the US.
Hopefully, with some enlightenment of the FDA
toward the humanitarian use of “congenital” devices in
adult patients, the precedence might extend to the very
small, unique and otherwise untreatable populations of
neonatal congenital heart patients. Without resistance
from the FDA, it might be possible to import these unique
but rarely used stents or to persuade one or more of the US
stent manufacturers to make these or similar “open-ring”
stents available even for this commercially non-profitable
group of patients.

Future stents
New intravascular stents continue to be developed
and improved for acquired vascular diseases in the adult
population. Secondarily, but presently only fortuitously
and certainly not “officially”, these new stents become
available for congenital and pediatric heart patients.
With some enlightenment of the FDA, hopefully some
Objective Performance Criteria (OPCs) can be agreed
upon between the professionals caring for these patients,
industry and the FDA which would allow not only
the approval of existing stents for congenital lesions, but
would permit and even encourage the development of
stents specifically for the pediatric/congenital population.
An alternative to the small open-ring stent might be a
small, but at the same time, a totally biodegradable stent.
Biodegradable stents have been developed primarily with
the goal of preventing re-stenosis, but up until now, have
not proven satisfactory. Such a small resorbable/degrad-
able stent, which is developed for larger coronary arteries,
could be ideal in order to “buy time” for severe stenosis of
major vessels in very small infants.
Complications of stent implants
With the exception of the inappropriate use of a stent in a
particular location, the complications of intravascular
stents in the pediatric and congenital populations, are
almost all related to the implant procedures, and not to
the stents themselves. Once successfully and accurately
implanted, and unlike the stents used in acquired adult
vascular diseases, there are very few late complications of
the stents themselves in pediatric/congenital patients.

This is particularly true for the currently available, new
generation of stents. Those late complications which have
occurred, are usually related more to specific peculiarities
of the underlying congenital lesions than to the stents
themselves. Complications can occur during implants
into any location in congenital lesions; however, implants
into the pulmonary arteries (Chapter 23) are technically
more challenging and result in more complications.
The most significant complication of the stents them-
selves is iatrogenic and occurs when an inappropriate
stent is implanted in a particular vessel. This occurs most
commonly when a small stent, which cannot be dilated to
the eventual adult diameter of the vessel, is implanted in a
growing patient. This, in turn, will eventually result in
stenosis of the vessel that will be of equal or greater
significance to the stenosis caused by the initial lesion. A
stenosis in a vessel due to a stent that is too small and can-
not be dilated any further, will require complex surgical
intervention to correct it. To relieve the stenosis due to
a small stent, the entire segment of the vessel must be
excised or the entire length of the stent/vessel must be
divided and patched, whether any other surgery is
required for that particular patient. The use of a stent that
knowingly will eventually be too small for the vessel, is
justified only in life-threatening situations, and/or when
the patient will require surgery in the area of the stent for
some other reasona for example a “conduit” exchange
necessitated for growth.
With the continued necessity of having to “make do”
with the materials available rather than having the

specific stents and/or specific equipment designed for
stent delivery in pediatric and congenital lesions, the
physician implanting stents in pediatric/congenital
patients with complex lesions must anticipate a variety of
problems with stent deployment and implant. In turn, the
operator must be prepared to handle these so they remain
“adverse events” and do not result in permanent adverse
sequelae for the patient.
The most important “treatment” of the complications of
stent implants, like all complications, is prevention! Tried,
true and established delivery equipment and techniques
are used as often as possible. Very careful attention must
be paid to all of the details of the procedures that have
been demonstrated to be successful as well as safe for
the implant of the stents. Very careful observation of the
catheter, wire, sheath/dilator, balloon/stent, and finally,
the position of the stent, is essential at all stages of the pro-
cedure. Taking “one step backward” and “regrouping” in
order to correct an erroneous position of any of the com-
ponents of the system at any time during the implant pro-
cedure helps to prevent complications or, at the very least,
prevents repetition of most of the preceding procedure.
“Short-cuts” in the techniques and changing to different,
not previously tested equipment or techniques, frequently
result in problems with delivery or implant of the stent.
New materials (wires, sheaths, balloons and even stents)
and new techniques using unproven materials or new
materials should be tested on animal models and then