Ebook Practical approach to catheter ablation of atrial fibrillation: Part 2

GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 135 Aptara, Inc.

PART

IV Ablation Procedures


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 136 Aptara, Inc.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 137 Aptara, Inc.

9 Circumferential Ablation
with PV Isolation Guided
by Lasso Catheter
Feifan Ouyang
Kazuhiro Satomi

Karl-Heinz Kuck

Recent studies have demonstrated that myocardium around the pulmonary vein
(PV) ostia plays an important role in the initiation and perpetuation of atrial fibrillation (AF) (1). This important finding has led to the development of segmental PV
ostial isolation (2,3), circumferential ablation (4), or isolation around the PVs
guided by 3-D electroanatomic mapping (5). Also, substrate modification with the
use of limited linear ablation (such as roof line and left isthmus line) (6,7) or ablations of the areas associated with complex fractionated electrograms (8,9) have
been demonstrated to improve the clinical outcome after PV isolation in patients
with AF inducibility.
The method most used in the majority of ablation centers is PV isolation either
using segmental PV isolation or circumferential complete PV isolation guided by 3-D
mapping. In these procedures the Lasso catheter recording within the PV plays an
important role in identifying electrophysiological connections between the PV and

the left atrium (LA). Also, electroanatomic mapping provides more precise information on the anatomy of atrial chambers and contributes to shorter fluoroscopic
time.
In this chapter we describe our circumferential ablation technique for PV isolation guided by the Lasso catheter and electroanatomic mapping in patients with
paroxysmal or persistent AF.

Dr. Kazuhiro Satomi is supported by the Research Grant Abroad of the Japan Heart Foundation and
Japanese Society of Electrophysiology, and the Research Grant Abroad of St. Jude Medical and Fukuda
Denshi. We thank Dr. Florian T. Deger for his assistance.

137


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 138 Aptara, Inc.

138

Part IV ■ Ablation Procedures

Complete PV Isolation Using 3-D Mapping
and Lasso Technique
The ablation procedure is routinely performed under sedation with a continuous
infusion of propofol in our center. Transesophageal echocardiography (TEE) is performed in all patients to rule out LA thrombi. Anticoagulation treatment with warfarin is stopped on admission and replaced by intravenous heparin to maintain partial
thromboplastin time at two to three times higher than the control value in all
patients. All procedures consist of the steps described below (5,10,11).

Transseptal Puncture
Three 8F SL1 sheaths (St. Jude Medical, Inc., Minnetonka, MN) are advanced to the
LA by a modified Brockenbrough technique in the majority of patients: two sheaths
over one puncture site and the third sheath via a second puncture site. One puncture
is always performed at the inferoposterior site of the foramen ovale for easy access to

the right inferior vein and the atrial myocardium (Fig. 9.1). After transseptal catheterization, intravenous heparin is administered to maintain an activated clotting time of
250 to 300 seconds. Additionally, continuous infusions of heparinized saline are connected to the transseptal sheaths (flow rate of 10 mL/h) to avoid thrombus formation or air embolism.

LA Reconstruction
Electroanatomic mapping is performed with a 3.5-mm-tip catheter (ThermoCool
Navi-Star or ThermoCool, Biosense-Webster, Inc., Diamond Bar, CA) during coronary sinus (CS) pacing, sinus rhythm (SR) or AF by using the CARTO system

Figure 9.1. The right and left images show, respectively, fluoroscopic right and left anterior oblique views
(LAO and RAO) during transseptal puncture. One puncture is always performed at the inferoposterior site
of the foramen ovale for easy access to the right inferior vein and the atrial myocardium. CS, coronary
sinus; His, His bundle; RA, right atrium.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 139 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

139

Figure 9.2. The left upper and lower images show right lateral and left lateral 3D-MR views of the LA. The middle and right images show, respectively, electroanatomic maps of the LA in the right lateral and left lateral view before
and after correction of map in same patient. The PV ostia (identified by angiography) are tagged by white dots. Note
that (a) in the MR imaging view the ostium of the right superior pulmonary vein (RSPV) are more anterior than the
ostium of the right inferior pulmonary vein (RIPV); (b) in the original map (middle images) the LA posterior wall
is not flat due to many mapped points within the right- and left-sided PVs, whereas in the corrected map in the right
images the LA posterior wall is very flat after the deletion of the points within the PVs on both sides; (c) the anterior wall is prominent due to points obtained with excessive pressure on the LA anterior wall in the original map in
the middle image, whereas the anterior wall is smooth after the deletion of these points in the corrected map in the
right image. RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein. See color insert 2.

(Biosense-Webster, Inc.) or the NavX system (St. Jude Medical, Inc.). Mapping is
only performed in the LA; all mapping points deep within the PV must be deleted to

ensure that the posterior wall is flat in the right lateral and left lateral views (Fig. 9.2)
during ablation.

Selective Venography of PV and Identification of PV Ostium
After LA reconstruction, each PV ostium is identified by selective venography
(Fig. 9.3) and carefully tagged on the electroanatomic map. We arbitrarily defined


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 140 Aptara, Inc.

140

Part IV ■ Ablation Procedures

Figure 9.3. The images show, respectively, fluoroscopic right and left anterior oblique views (RAO and
LAO) of the left atrium. The PV ostia are marked by points. The lines indicate the ablation line around
the right-and left-sided PVs. CS, coronary sinus; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein.

any point with clear PV-LA inflection and marked the opposite points with perpendicularity to the PV on the right anterior oblique (RAO) 30Њ or left anterior oblique
(LAO) 40Њ (Fig. 9.2). This step is the most important part to achieving a successful
PV isolation. In our experience, the misunderstanding of the PV ostium may sometimes make the ablation more difficult or create a potential risk for PV stenosis. For
example, the isolation of the left-sided PVs in the setting of a narrow ridge between
the left atrial appendage and the left PVs can be very difficult if the anterior edge of
the left PV ostia is inappropriately marked in the left atrial appendage. On the other
side, severe PV stenosis can be produced if the PV ostium is tagged inside the PVs
(12,13).


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 141 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

141

Figure 9.4. Fluoroscopic right and left anterior oblique views (RAO and LAO) show two Lasso catheters
within right- and left-sided PVs, mapping catheter (Map) in left atrium and catheter inside coronary sinus
(CS). Numbers indicate the location of the electrodes of the Lasso catheter. RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior
pulmonary vein.

Double Lasso Technique
Two decapolar Lasso catheters (Biosense-Webster, Inc.) are placed within the ipsilateral superior and inferior PVs or within the superior and inferior branches of a common
PV before radiofrequency (RF) delivery in the majority of patients with AF (Fig. 9.4).
In our series of more than 1,300 AF ablations, in only 2% of patients could only one
Lasso catheter be placed in the PVs due to very difficult transseptal puncture or
manipulation of the sheaths.
The Lasso catheters within the ipsilateral PVs should be located with the catheter
placed in a stable position to obtain a good signal during the procedure. If the Lasso
catheter is placed too distally, the PV potential could be too small or unrecordable,
especially in patients with a damaged atrium due to longstanding AF. If the Lasso
catheter is located in the LA outside of the PV, it could result in misunderstanding of
the LA and PV signal. In addition to the exact tagging of the PV ostium on the
CARTO map, keeping in mind the Lasso catheter position and the placement of its
electrodes enables mapping by using only an electroanatomic map without frequent


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 142 Aptara, Inc.

A

B

Figure 9.5. A: 3-D anatomic maps and MR images combined with CARTO map of the LA in a left lateral (LL),
posteroanterior (PA), and right lateral (RL) view are shown. Note that (a) the angiographic ostia of all PVs are tagged
with white points; (b) the right and left continuous circular lesions are marked by multiple red dots around the PVs;
(c) the two brown dots located in the right posterior CCLs and in the left anterior CCLs indicate the sites of simultaneous isolation of the ipsilateral PV when both CCLs are complete. B: MRI-derived, virtual endoscopic views of
the junction of the right- and left-sided PVs and LA on CARTO merge imaging are shown. The ostia of the RSPV
and RIPV are shown in the left panel and LSPV, LIPV, and LAA in the right panel. Note that (a) the right and left
CCLs are marked by multiple red dots around the PVs in the left and right panels; and (b) CCLs are located on the
ridge between the left PV and the LAA in the right panel. CCLs, continuous circular lesions; RSPV, right superior
pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; LAA, left atrial appendage. See color insert 2.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 143 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

143

Figure 9.6. 3-D anatomic maps of the LA by NavX in posterior-anterior and anterior-posterior views. The angiographic ostia of all PVs are tagged with black lines. The right and left CCLs are marked by multiple red dots around
the PVs. Two Lasso catheters are located in the left and right PVs to confirm isolation of both PVs. CCLs, continuous circular lesions; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior
pulmonary vein; LIPV, left inferior pulmonary vein; LAA, left atrial appendage; MVA, mitral valve annulus. See color
insert 2.

use of fluoroscopy during the procedure, which contributes to shorter fluoroscopic
and procedure time.

Continuous Circular Lines Surrounding the Ipsilateral PVs
Irrigated RF energy is delivered with a target temperature of 45ЊC, a maximal power
limit of 40 W, and an infusion rate of 17 mL/min. In all patients, maximal power of
30 W is delivered to the posterior wall to avoid the potential risk of LA–esophageal
fistula. RF ablation sites are tagged on the reconstructed 3-D LA. RF energy is

applied for 30 seconds until the maximal local electrogram amplitude decreases to less
than 70% or double potentials appear, and the sequence of PV activation recorded
from the double Lasso catheters changes. RF ablation is performed in the posterior
wall more than 1 cm and in the anterior wall L5 mm from the angiographically
defined PV ostia (Figs. 9.5, 9.6).

Procedure Endpoint
More than 90% of right PVs are isolated by completing anatomic continuous circular lines (CCLs) alone, however 30% of left PVs are still conducted after the
completed CCLs even in highly experienced physicians (Fig. 9.7). The remaining
conduction gaps can easily be found with 3-D mapping and two Lasso catheters
within the ipsilateral PVs. The additional applications at the conduction gap
between the LA and PV are delivered according to the activation sequence of the
Lasso catheters. In patients with paroxysmal or persistent AF, the ablation endpoint of CCLs is defined as absence of all PV spikes during SR documented with
the two Lasso catheters within the ipsilateral PVs at least 30 minutes after PV isolation. Termination of AF is not included in the endpoint in our procedure. Electrical cardioversion is performed after complete isolation of the bilateral PVs in
case of AF persistence.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 144 Aptara, Inc.

144

Part IV ■ Ablation Procedures

Figure 9.7. Tracings during sinus rhythm are ECG leads I, V1 and intracardiac electrograms recorded
from two Lasso catheters within the left superior and inferior pulmonary veins (LSPV, LIPV), a mapping
catheter (Map), a catheter inside the coronary sinus (CS) during RF application in a patient with paroxysmal AF. Note a simultaneous isolation of both LSPV and LIPV when the right CCLs are complete. CCLs,
continuous circular lesions; LA, left atrium; PV, pulmonary vein.

Electrophysiologic Findings of Double Lasso Catheters
during CCLs

The double Lasso technique provides better information on LA-PV conduction and
interesting electrophysiologic findings about the PV activation. This technique is also
helpful for complete PV isolation by CCLs. The comprehension of the electrophysiologic
findings recorded by the Lasso catheter is the most essential for electrophysiologic PV
isolation. Careful analysis of the signal at the LA-PV is required to avoid a wrong
interpretation.

Complete PV Isolation by CCLs
Our studies have demonstrated that CCLs can be performed during SR or CS pacing or during AF (5,11). During SR or CS pacing, CCLs resulted in progressive prolongation and sequence change of PV activation recorded from two Lasso catheters
within ipsilateral PVs, and finally isolation of the ipsilateral PVs is achieved without
amplitude reduction of the PV spike (Fig. 9.8). We immediately stop the RF


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 145 Aptara, Inc.

A

B
Figure 9.8. A: 3-D anatomic maps of the LA in a left lateral view. Note that (a) the left continuous circular lesions
(CCLs) are marked by multiple red dots around the PVs; (b) the two sites with a brown dot located in the left postero-superior CCL indicate the change of PV sequence and another brown dot in the left anterior CCLs indicates
simultaneous isolation of the ipsilateral PVs. See color insert 2. B: Tracings during sinus rhythm are ECG leads I, V1
and intracardiac electrograms recorded from two Lasso catheters within the left superior and inferior pulmonary veins
(LSPV, LIPV), a mapping catheter (Map), a catheter inside the coronary sinus (CS) during RF application in a patient
with paroxysmal AF. Note: (a) the earliest activation of PV recorded by Map (arrow); (b) a sequence change of both
LSPV and LIPV and all LIPV signals significantly delayed in the second beat compared to the first beat during the
RF application at left anterior CCLs. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 146 Aptara, Inc.

146

Part IV ■ Ablation Procedures

C
Figure 9.8. (continued) C: Note: (a) a simultaneous isolation of both LSPV and LIPV when the left CCLs are
complete at the left posterior region; (b) the earliest activation of PV recorded by Map (arrow). LA, left atrium, PV,
pulmonary vein.

application to avoid the potential risk of PV stenosis in case of ablation catheter dislodgement into the PV. In our previous experience without using double Lasso techniques, the application at the inside the PV causes to the attenuation of the PV signals or isolation of only the distal part of the PV and makes identification of the PV
activation sequence more difficult (Fig. 9.9).
During AF, the disorganized PV activation within the PVs becomes progressively
organized with the same or similar PV activation sequences and prolonged cycle
length (CL), and finally the ipsilateral PVs are simultaneously isolated. The fibrillatory CL recorded from the CS was also longer after ablation than that before ablation in patients without the termination of AF (Fig. 9.10). The ipsilateral PV spikes
disappeared simultaneously in more than 90% of patients at completion of the respective CCL during SR or AF. This important finding provides the scientific evidence
that complete PV isolation by CCL can be confirmed in clinical practice by using a
single Lasso catheter in one of the ipsilateral PVs.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 147 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

147

Automatic Activity and Tachycardia in PVs
After the complete isolation of the PVs, regular or irregular automatic activity dissociated from the atrial activity was observed in L95% patients. Also, induced or spontaneous sustained fast PV tachyarrhythmias were observed within the isolated PV
after complete isolation of the PV in L45% patients (Fig. 9.11). The high incidence
of automatic activity and fast PV tachyarrhythmias within the PVs may be due to
more myocardium within the isolated area compared with previous studies using

segmental PV isolation.

AF Termination during CCLs
In our recent study, 51 patients with paroxysmal AF underwent complete PV isolation during AF. After complete PV isolation, external cardioversion (CV) was
required to terminate AF only in five patients (9.8%); in the remaining 46 patients
(90.2%), AF termination occurred before or immediately after complete PV isolation

A
Figure 9.9. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso
catheters within the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV), a
mapping catheter (Map d, Map p) and a catheter inside the coronary sinus (CS) in a patient with paroxysmal AF. A: Note that (a) significantly delayed second potential (PV) following the left atrial (LA)
potential only recorded by Lasso catheter in RSPV; (b) automatic activity dissociated from the atrial and
PV activity (*) in both RSPV and RIPV, suggesting that a distal part of the CCLs of the right PVs is
isolated. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 148 Aptara, Inc.

148

Part IV ■ Ablation Procedures

B
Figure 9.9. (continued) B: Note the elimination of the second potential (PV) by a single application at
the posterior region of RSPV. This phenomenon suggests that a junctional region between the LA and
RSPV was separately isolated.

(14). Importantly, a single PV as AF origin was demonstrated in five patients (9.8%),
in whom sustained PV fibrillation or tachycardia was always observed within the PV
before isolation during AF and after isolation during SR. However, in patients with

persistent AF lasting more than 7 days and less than 1 year, AF termination only
occurred in 30% of cases (11). Also, in the majority of cases, AF termination occurred
before isolation of the bilateral PVs. AF termination in patients with paroxysmal or
persistent AF may be explained by the fact that CCLs eliminate a number of random
re-entries and consequently result in inability of AF perpetuation. Based on our data,
AF termination should not be the endpoint for catheter ablation, because AF terminated before complete isolation in most cases.
Electrical cardioversion is performed after complete isolation of the bilateral PVs
in case of AF persistence. Interestingly, in some patients the PVs are still conducted
with marked conduction delay during SR immediately after cardioversion. The conduction through CCLs between LA and PV may depend on the cycle length (Fig. 9.12).


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 149 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

149

A

B
Figure 9.10. Tracings are ECG leads I, II, V1 and intracardiac electrograms recorded from two Lasso catheters
within the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV), a mapping catheter
(Map), a catheter inside the CS, and a catheter at the His bundle region (HBE) in a patient with persistent AF.
In (A), note that the PV spikes recorded within the RSPV and RIPV are disorganized, with beat-to-beat variation of PV activation sequences and cycle length (CL) before the right-sided continuous circular lesions (CCLs).
In (B), note that the PV spikes within the RSPV and RIPV become organized with a similar beat-to-beat PV activation and a variation of CL during RF application on the CCLs. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 150 Aptara, Inc.

150

Part IV ■ Ablation Procedures

C
Figure 9.10. (continued) In (C), note that the slow PV spikes with identical activation sequence (*) suddenly disappear when CCLs are completed during RF application.

A
Figure 9.11. Tracings during sinus rhythm are ECG leads I, II, V1 and intracardiac electrograms recorded from a Lasso
catheter within the left common pulmonary vein (LCPV), a catheter inside the coronary sinus (CS) and a mapping
catheter (MAP) in a patient with paroxysmal AF. Numbers indicate the cycle length of PV activation. A: The initiation
of AF by PV tachycardia (PV) originating from the LCPV before PV isolation with an irregular cycle length. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 151 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

151

B

C
Figure 9.11. (continued) B: 1. AF termination by complete CCLs around LCPV; 2. Continuous PV tachycardia
within the LCPV and sinus rhythm (SR) in the atrium, indicating exit block between PV and LA. C: 1. Spontaneous
termination of PV tachycardia without prolonged cycle length; 2. LCPV isolation is confirmed by no PV activation
following LA signals. A, LA activation, PV, pulmonary vein activation.


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 152 Aptara, Inc.

152

Part IV ■ Ablation Procedures

A

B
Figure 9.12. Tracings are ECG leads I, II and intracardiac electrograms recorded from two Lasso catheters
within the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter
(Map), a catheter inside the coronary sinus (CS), and a catheter at the His bundle region (HBE) in a patient
with persistent AF. A: Note: (a) persistent tachycardia demonstrated by surface ECG and CS catheter; (b) automatic activity dissociated from the atrial activity (*) in both LSPV and LIPV, resulting from complete left PV
isolation. B: 1. Sinus rhythm is recovered restoration after external cardioversion, 2. Marked delayed PV signals (*)
in LSPV and LIPV, showing that PVs still have conduction during sinus rhythm. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:26AM Page 153 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

153

C
Figure 9.12. (continued) C: A simultaneous isolation of both LSPV and LIPV by a single application.

Therefore complete PV isolation should be confirmed during SR according to our
experience.

Identification of PV Potential and Far-Field Atrial Potential
Identification of the PV and far-field atrial potentials on the Lasso recording is very
important during a procedure. In anatomy, the superior vena cava (SVC) is located

just anterior to the right superior PV. Also, a myocardial sleeve from the RA can
extend deeply into the SVC, and produce a discrete spike within the SVC (15–17).
Therefore, the far-field potentials originating from the SVC can be recorded within
the RSPV in patients undergoing PV ablation (17). Generally, these far-field potentials
are small and are recorded only in the anterior part of the Lasso catheter within the
RSPV (Fig. 9.13).
On the other hand, PV activations from both left PVs are generally fused with
the activation from the left atrial appendage (LAA) during SR. Both fused components can be separated by pacing from the catheter within the CS or LAA (18). The
second PV potential follows the far-field LAA potential during pacing at the LAA or
pacing at the CS. The amplitude of each potential depends on the location of the
Lasso catheters. The Lasso catheter just at the ostium of the PV demonstrates a farfield potential of high voltage (Fig. 9.14).
For the ablation of the left PVs, we usually start the RF applications at the roof
and the anterior superior part of the ridge between the left superior PV and the LAA
during SR. When these lesions are continuous and transmural, the PV signals are


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 154 Aptara, Inc.

154

Part IV ■ Ablation Procedures

A

B
Figure 9.13. A: Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within
the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV) and a catheter inside the coronary
sinus (CS) in a patient with persistent AF. Ipsilateral right pulmonary vein tracings are shown during AF. Note that the
slow PV spikes with identical activation sequence (*) suddenly disappear when CCLs are completed during RF application. Sharp potentials still persist in RSPV 6–7 to 9–10 (▼). B: In the left panel, tracings are ECG leads I, V1 and intracardiac electrograms recorded from a Lasso catheter within the RSPV, a mapping catheter in the superior vena cava
(SVC) and a catheter inside the CS. Fluoroscopic right and left anterior oblique views (RAO and LAO) are shown in

the right panel. Note: (a) Dissociated PV activation recorded by Lasso catheter within the RSPV (*); (b) The ablation
catheter placed in the SVC opposite to RSPV 7–8 to 9–10 (catheter positions shown on the right panel) records sharp
potentials (▼) with a timing identical to the residual potentials in the RSPV (despite AF).


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 155 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

155

separated from the LAA potential and become visible in almost all patients (Fig. 9.15).
This can easily facilitate RF ablation at the ridge between the left PVs and the LAA.
After the RF lesions at the ridge, triple potentials consisting of double LAA potentials and the one PV potential were occasionally observed from the Lasso catheter due
to the conduction delay in some patients (Fig. 9.16). However, it is more difficult to
distinguish both PV and far-field LAA potentials during AF. Careful judgment of activation sequence during ablation (such as organized PV activation or prolonged CL
of PV activation) can help identify both components. Furthermore, it is quite difficult to assess the reduction of local signal by the RF application during AF. This may
result in inadequate applications in some areas. In our experience, stable SR can be
maintained after isolation of the right-sided PVs in most patients with failed cardioversion before ablation. Therefore, we strongly recommend performing the left
CCLs during SR in clinical practice.

A
Figure 9.14. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within
the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map), and a
catheter inside the coronary sinus (CS) during RF application for the left pulmonary veins. A: In the left panel note
that during CS pacing RF application eliminates spiky potentials recorded by Lasso catheters in the LIPV (▼) and
two separate components of signals are still recorded in the LSPV (*). In the right panel, during SR the two components of the signal in LSPV are fused. LA, left atrium activation (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 156 Aptara, Inc.

Figure 9.14. (continued) B: A mapping catheter placed in the left atrial appendage (LAA) records sharp
potentials (arrow) with timing identical to the residual potentials in the LSPV (*). This phenomenon
shows that CS pacing could lead to misunderstanding of a delayed LAA potential as PV potential.

A
Figure 9.15. A: 3-D anatomic maps of the LA in a posterior-anterior view. Note that (a) the left PV
ostium is marked by white dots; (b) the left continuous circular lesions (CCLs) are marked by multiple red
dots around the PVs; (c) the one site with a brown dot located in the left anterior-superior CCLs indicates
the change of PV activation sequence. See color insert 2. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 157 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

157

B
Figure 9.15. (continued) B: Tracings are ECG leads II, V1 and intracardiac electrograms recorded from two Lasso
catheters within the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter
(Map) and a catheter inside the coronary sinus (CS) during RF application for the left pulmonary veins. The change
of activation sequence of both the LSPV and the LIPV, and the marked delay of all LSPV signals in the second beat
compared with the first beat during RF application at the left antero-superior CCL indicates that conduction block
created by the ablation has made the PV spike visible. LA, left atrium; PV, pulmonary vein.

Recovered PV Conduction after the Initial Ablation Procedure
The recurrence rate after initial PV isolation seems to be different depending on
the ablation technique and the follow-up. In our experience, without any blanking period, the recurrence rate of atrial tachyarrhythmias was 25% in patients with
ablation during stable rhythm and 37.5% in patients with ablation during AF during more than 6 months of follow-up. Interestingly, recovered PV conduction has

been demonstrated in 80% to 90% of patients with recurrent tachycardia after
CCLs, and the recovered PV activation presented as significant delay during SR
compared with that before the initial ablation (Fig. 9.17). During the second
procedure, the conduction gap was found in all regions of the previous CCLs. All
conduction gaps were easily identified in the previous CCLs by using two Lasso
catheters within the ipsilateral superior and inferior PVs, and could be successfully
closed by a few RF applications in the previous CCLs during the second procedure
(Fig. 9.17).


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 158 Aptara, Inc.

158

Part IV ■ Ablation Procedures

Interestingly, the surface ECG showed a constant P-wave morphology and an
identical atrial activation sequence before complete PV isolation in some patients with
recurrence of PV tachycardia. The atrial tachycardia (AT) with irregular or regular CL
resulted from the PV tachycardias, sometimes from the PV fibrillation, conducting
through the gap between the PV and the LA, which was demonstrated by Lasso
catheters within the respective ipsilateral PVs. After complete PV isolation, SR
occurred in the setting of continuous PV tachyarrhythmias within ipsilateral PVs (Fig.
9.18). The PV tachyarrhythmia required external cardioversion for termination during SR, strongly suggesting that the PV tachyarrhythmia is due to re-entry (14). This
interesting finding using our techniques suggests that a single PV can act as AF substrate.
Our data were consistent with previous studies showing that recovered PV conduction is a dominant finding in patients with recurrent atrial tachyarrhythmias after the
initial procedure (10,19). Importantly, the majority of patients were free of recurrence
after the second procedure. The clinical success was Ϸ95% after permanent complete
PV isolation including the second ablation procedure in patients with paroxysmal and
persistent AF. These data strongly support the concept that permanent PV isolation

should be the endpoint of CCLs.
In patients without recovered PV conduction, we attempted to uncover non-PV
foci triggering AF by stimulation and provoked maneuvers to abolish all non-PV foci

A
Figure 9.16. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within
the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map), and a
catheter inside the coronary sinus (CS) during RF application for the left PV. A: Note that the signals on the Lasso
catheters in LSPV and LIPV are isolated simultaneously after a sequence change of Lasso recordings without any
applications at the anterior part of the LSPV. (continued)


GRBQ381-3653G-C09[135-166].qxd 2/29/08 8:27AM Page 159 Aptara, Inc.

Chapter 9 ■ Circumferential Ablation with PV Isolation Guided by Lasso Catheter

159

B

Figure 9.16. (continued) B: Note that the

C

local potential recorded by a mapping
catheter placed on at the anterior region of
the LSPV shows three components of signals before isolation, indicating double
potentials of LA and PV potential, respectively (LA1, LA2, PV). This phenomenon
may suggest a spontaneous block at the
anterior region of the left PV (between left

PV and LAA). C: 3-D anatomic maps of the
LA in a posterior-anterior view. Note that
(a) the left PV ostium is marked by white
dots; (b) the left continuous circular lesions
(CCLs) are marked by multiple red dots
around the PVs; (c) the region showing
triple potential by a mapping catheter is
marked by a green dot; (d) the two sites with
a brown dot located in the left posterior
CCLs indicate the change of PV activation
sequence and another brown dot in the left
anterior inferior CCLs indicates simultaneous isolation of the ipsilateral PV without
any applications at the anterior region of the
left PV. See color insert 2.