Andersons pediatric cardiology 1125

FIG.42.33 Aneonatewithcriticalpulmonaryvalvestenosis.(A)Baseline
rightventricularangiogramdocumentingseverestenosisofthepulmonary
valvewithonlyanarrowjetenteringthemainpulmonaryartery.(B)Initial
balloonvalvuloplastywithatightwaist/hourglassappearance—notethe
wirepositionthroughthepatentductusarteriosusintothedescending
aorta.(C)Balloonbeingfullyinflatedwithoutaresidualwaist.(D)Right
ventricularangiogramdocumentingsubvalvarnarrowingafterballoon
pulmonaryvalvuloplasty.

Thechoiceofguidewireisdependentontheoperatorandontheageofthe
patient.Inolderpatientswhoarestableduringtheprocedure,itwouldbe
reasonabletouseahydrophilicwiretogainadistalpositioninthepulmonary
artery,exchangingitforastiffexchangewire,whichthencanbeusedfor
advancingtheballooncatheter.Inneonates,acoronaryangioplastywirecanbe


passedthroughthevalveandusedtodelivertheangioplastycatheter.
Thechoiceofthetypeoftheinitialballoonusedoftendependsonthe
availabilityateachinstitution.Ingeneral,insmallpatients,fairlycompliant
balloonssuchastheTyshakIIorTyshakminiareoftenused,whereasinolder
patientslesscompliantballoons,suchastheZMedII,mayofferadvantagesdue
tothehigher-ratedburstpressure.Somecentershaveevenusedunconventional
balloonssuchastheInoueballoon,eventhoughthesearelessdesirablechoices
fortheprocedure.90
Thechoiceofdimensionoftheballoonhasbeenthesourceofmuch
discussion.Itisclearthattheballoonmustbeoversizedinrelationtothe
dimensionofthepulmonaryvalve,butthereisevidencethatsizesinexcessof
120%to125%ofthepulmonaryvalvearenomoreefficaciousatreducingthe
severityofpulmonarystenosisyetcreatemoreproblemsintermsofsubsequent
pulmonaryincompetenceorothercomplications.91,92Anexceptioncouldbe
arguedincaseswherethevalveismarkedlydysplasticandstenosed.Thereare

fewdetaileddataandlittleevidenceforchoosingthelengthoftheballoon.
Shorterballoonsmaybemoredifficulttostabilizecentrallyoverthepulmonary
valve,whereaslongerballoonscarrymoreriskofdamagetothetricuspid
valve,88atrioventricularnode,93anddistalpulmonaryarteries.Simple,intuitive
choicesarea20-mmballoonforneonatesandinfants,a30-mmballoonfor
children,and40-to50-mmballoonsforadolescentsandadults.69
Inmostcases,therefore,acoaxialangioplastyballoonoftheappropriatesize
isselectedandtrackedovertheguidewiretothepulmonaryvalve.Iftheballoon
failstotrackthroughtherightventricle,thenthereisagoodchancethatthe
catheterhaspassedbehindsometensionapparatusofthetricuspidvalve.Inthat
caseitisbettertowithdrawthecatheterandguidewireandrecrossthetricuspid
valvesoastoobtainabetterposition.Toforcetheangioplastyballoononwardis
disadvantageousbecausetheballoonwouldbedrawninadenaturedformback
throughthetricuspidvalvewiththepotentialforseriousdamage.88
Whenitisdifficulttocrossthepulmonaryvalvewiththechosendimensionof
balloon,itisoftenbettertoexchangetheballoonangioplastycatheterfora
smallerone,evenassmallasa3-mmcoronaryangioplastyballoon,inorderto
predilatethevalvebeforereturningwiththeoriginal.94Inneonates,trackability
oftheballoonacrossthevalvecanbeimprovedifthewirehasbeenpositioned
acrossthearterialductandiscompressedattheinguinalsiteexternally.
Balloonpreparationfollowsstandardtechnique,asoutlinedinChapter19.In
unstablepatients,theballoonshouldbepreppedandreadytousepriorto


crossingthepulmonaryvalve.Ideallyaninflationdeviceisusedthatcanbe
operatedwithasinglehandwhiletheotherhandcontrolsthewireposition.This
simultaneouscoordinationbetweenballoonpositionandinflationaidsin
achievingacentralpositionoftheballoonacrossthevalveduringinflation.
Whilewatchingthehourglassimpressionofthepulmonaryvalveontheballoon
duringinflation(seeFig.42.29),theballoonmightprolapseforwardor

backwardandmanipulationoftheballoonandtheguidewiremayberequired.
Cardiacoutputcontrolthroughrapidventricularpacingisusuallynotrequired
forballoonpulmonaryvalvuloplasty.Theballoonisinflateduntilitswaistis
seenonfluoroscopytohavebeenabolished.Applicationofhigherpressuredoes
notserveanyusefulpurposebeyondthepointatwhichparallelwallsofthe
balloonhavebeenreached,anditcarriesagreaterriskofrupture.Ifthereisstill
aresidualhourglassimpressionontheballoonduringinflation,thenthe
ventriculoarterialjunctionitselfmaybehypoplasticandtheprocedurewillhave
limitedbenefit.Insomepatientswithadysplasticpulmonaryvalve,attemptscan
bemadetouseaballoonthatmayaccepthigherinflationpressures,inparticular
ifalow-pressurecompliantballoonsuchastheTyshakIIwasusedfortheinitial
inflation.
Followingthefirstinflation,mostoperatorsinflateoneormoretimesand
studythewaythattheballooninflatesanddeflatestodeterminewhetheran
hourglassimpressionisstillcausedbythepulmonaryvalve.
Afterinflationandcarefulwithdrawal,thepressureintherightventricleand
thegradientacrossthepulmonaryvalveshouldberecorded.Thepositionofthe
wirecanbepreservedusingamonorailcatheteroranend-holecatheteranda
Tuohy-Borstadaptor.Alternatively,apressurewirecanbeusedtoassessthe
valvarandsubvalvargradientwithouthavingtocompletelywithdrawthewire
intotherightventricle.Inpatientsbeyondinfancy,recrossingthevalvewitha
balloon-tippedcatheterisusuallyeasilyaccomplished.Thisdiffersfromthe
procedureonneonateswithsevereorcriticalpulmonaryvalvestenosis,wherean
infundibularsubpulmonarynarrowingmaybecomemoreapparentoncetheright
ventricularpressuredecreasesaftervalvuloplasty.
Carefulpullbackwillshowwhetheranyresidualgradientisconfinedtothe
pulmonaryvalveorindeedispresentinthesubvalvarrightventricularoutflow
tract.Ifthereisasignificantvalvargradient,thedecisiontoreattemptdilation
withalargerballooncanbemade.Thepresenceofasignificantsubvalvar
gradientisawell-describedphenomenonafterdilationofthepulmonaryvalve

andcanhaveseriousconsequenceswithalow-cardiac-outputstate.Thisisthe