Andersons pediatric cardiology 1127

FIG.42.34 A15-year-oldmalewithmoderatepulmonaryvalvestenosis.
Top,Rightventricularangiogramdocumentingathickenedanddoming
pulmonaryvalve.Bottom,Doubleballoonpulmonaryvalvuloplastyusing
twohigh-pressureballoons.A-planeprojectionstotheleftandlateral
projectionstotheright.

Theuseofthemultitrackdoubleballoonmitralcommissurotomysystem,


employingtwocomplementaryangioplastycathetersdesignedtotrackalongthe
sameguidewire,hasbeenreportedinadultswithpulmonarystenosis.111
Althoughthistechniqueoffersaneasierapproachandonelessvenouspuncture
thantheconventionaldouble-balloontechnique,againitoffersanadvantage
onlyifasingleballoonofappropriatedimensionisnotavailable.Similarly,
angioplastycatheterswithmultipleballoons,bifoilandtrefoil,mountedin
parallelononeshaft,havebeendescribed,112aswellasatechniqueusingthree
separateangioplastyballoonswithacomplicatedformuladescribedfortheir
overalldimensions.113Suchballoonsorsystemsaswellasthedouble-balloon
techniquearearguedbytheirproponentstofacilitatesomeresidualantegrade
flowduringinflationintherightventricularoutflowtract.Thisseemsunlikely
whenthecorrectoversizeddimensionischosen.Inaddition,theyarebulkyand
havebeenlargelysupersededbymoremodernlargesingleballoonswithlower
profilesneedingsmallersheaths.
Althoughallthesetechniqueshavehadhighlyeffectiveandwell-sustained
results,ithassincebeenshownthatwhereasingleballoonisavailableforthe
appropriatedimension,noadvantageisconferredbyusingmultipleballoons.114
Itisimportant,nonetheless,thatalloperatorshaveanunderstandingofthese
techniquesaswellasknowledgeoftheequipmentthatisavailableintheirown
locallaboratoriesbecausethefinaldecisionmaybemadeonthebasisofsupply
anddemandofequipment.

AdverseEvents
Comparedwithmanyotherproceduresperformedinthecongenital
catheterizationlaboratory,balloonpulmonaryvalvuloplastyisusuallyafairly
safeprocedurewithlowrisks.BasedondatafromtheC3POregistry,the
procedurehasbeenclassifiedasriskcategory2(outof4)forpatients1monthof
ageorolder,andasriskcategory3forneonatesyoungerthan1monthofage.115
Acutecomplicationsofballoondilationofthepulmonaryvalvearerare,and
mostofthesearenonspecifictopulmonaryvalvuloplastyandrepresentgeneral
catheterizationrelatedadverseevents.Theseincludeadverseeventsrelatedto
anesthesia,arrhythmiasandconductionanomalies,vascularandcardiactrauma,
aswellasvascularentrysiterelatedcomplicationssuchasfemoralvenous
occlusionrelatedtotheinterventionthatmaybedemonstratedinmorethan20%
ofpatientsrequiringfurthervenousaccess.116
Tricuspidvalveinjuryandseverereactivesubpulmonarystenosisaresomeof


therarebutmorespecificandsignificantprocedure-relatedadverseeventsthat
havebeendescribed.Ruptureofthepulmonaryartery/rightventricularoutflow
tractisexceedinglyrareandcanbealmostcompletelyavoidedwhenusingthe
recommendedballoontoannulusratioof120%to125%.
Balloondilationhasprovedtobeverysuccessful,andithasyieldedminimal
immediatecomplications.Outof822proceduresenteredintotheVACA
Registry,includingcasesofcriticalpulmonarystenosis,themortalitywas
reportedas0.24%,andthemajorcomplicationrateonly0.35%.117Inasmaller
multicenterseriesof172patients,excludingcriticalpulmonarystenosis,there
wasnomortalitywithemergencysurgeryrequiredinonlyonepatient(0.58%)
whosufferedperforationoftherightventricularoutflowtract.118Resultsfrom
theImprovingPediatricandAdultCongenitalTreatmentregistryof268patients
undergoingballoonpulmonaryvalvuloplastydocumentedacuteadverseevents
duringthesameepisodeofcarein7.1%ofcases,withnomajoradverseevents

andnounplannedsurgeries.119
ResultsfromtheC3POregistry(211casesofballoonpulmonary
valvuloplasty)documentedanincidenceof9%forlow-severityadverseevents
(levels1to2)and3%forhigherseverityadverseevents(levels3to5).120Only
onemajoradverseeventwasreportedinthisstudy,whichwasanepisodeof
ventricularfibrillationduringballoonpulmonaryvalvuloplastyrequiring
electricaldefibrillation.Bymultivariateanalysis,independentriskfactorsfor
anyadverseeventwerepatientagebelow1monthandoperatorexperienceof
lessthan10years.
Duringinflationoftheballoon,transientbradycardiaandhypotensionmaybe
observed.Thiseffectrecoversquicklyafterdeflationoftheballoon.Apatent
ovalforamenoranatrialseptaldefecthelpstopreservesystemicventricular
outputduringocclusionofthepulmonaryarteries.Tominimizetheseeffects,
inflationoftheballoonshouldnotbemaintainedformorethanasecondortwo.
Withthemoderndesignofsheathsandcathetersandimprovedtechniques,
lossofbloodisminimal.Manipulationofthecatheterorwireintherightheart
canprovokearrhythmia,rightbundle-branchblock,andeventransientor
permanentcompleteheartblock.Othercomplicationsincludestrokeorseizures
duetoemboliccomplicationsinthecontextofapotentialright-to-leftatrial
shunt.
Ruptureoftheballoonathighpressuresofinflation,pulmonaryarterial
tears,121perforationoftherightventricularoutflowtract,118andruptureof
tricuspidvalvarpapillarymuscleshaveallbeenreported.87,122Failureof