Andersons pediatric cardiology 570
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representsamajorcauseofmorbidity,increasedlengthofhospitalstay,andcost.
AchildwithSVTpriortosurgerywilllikelystrugglewithitaftersurgery.This
isaconsequenceofavarietyoffactorsincludingbutnotlimitedtoexogenous
andendogenouscatecholamines,electrolyteabnormalities,operativeswelling,
andscarring.AnytypeofSVTcanbeseeninthepostoperativeperiod.Although
typicalreentrantSVT(AVNRTandAVRT)andEAToccurinyoungerchildren
undergoingcongenitalheartdiseasesurgery,asthecongenitalheartdisease
populationages,theincidenceofatrialflutterandAFincreases.
AchildwithapreoperativereentrantorautomaticSVTmechanismshouldbe
consideredforcatheterablationpriortocongenitalheartdiseasesurgery.This
shouldbethecasewhereanatrialcommunicationwillbeclosedinsurgeryand
couldbeusedtoaccesstheleftatriumpreoperativelyorinpatientssuchasthe
single-ventriclepopulation,wheresurgerygenerallywilldecreaseaccesstothe
atrium.
EATiscommoninsurgicallyrepairedcongenitalheartdiseaseand,likemost
postoperativearrhythmias,canbeassociatedwithsignificanthemodynamic
compromise.InastudybyClarketal.,univariateanalysisdemonstratedthat
youngerage,lowerweight,single-ventriclephysiology,longercardiopulmonary
bypasstime,needfordelayedsternalclosure,andgreateranatomiccomplexity
wereassociatedwithpostoperativeEAT.215Theincidenceamongsingleventriclepatientswas16%;ofthose,54%werelessthan30daysofage.
Multivariableanalysisconfirmedyoungerageatsurgery(<30days)andtheuse
ofmilrinoneasindependentpredictorsofEAT.ThusEATwasafrequent
complicationofcongenitalheartdiseasesurgeryinneonates.
Somepatientswillbenefitfromtheuseofapreoperativeantiarrhythmic
agentstopreventpostoperativearrhythmias.Inanadultpopulation,preoperative
oralamiodaroneinpatientsundergoingcomplexcardiacsurgerywasfoundtobe
toleratedandtosignificantlyreducetheincidenceofpostoperativeAFandthe
durationandcostofhospitalization.216Althoughthesedatarefertoanadult
population,thisstrategycouldbeconsideredinanadultcongenitalpopulation
whereAFisbecomingmoreofaclinicalissueorinchildrenwithsignificant
preoperativeatrialarrhythmias,suchasAForflutterinassociationwithEbstein
malformationofthetricuspidvalveormitralvalvedisease.
Operatively,theatrialmazeprocedurecanbeincorporatedintothesurgical
management.Incertainproceduresthiscanbelimitedtoeithertherightorleft
atrium,dependingontheanatomicsubstrate.In2006,thegroupfromtheMayo
Clinicdescribed99patientswithcongenitalheartdiseaseandassociatedAFor
flutterwhounderwentaconcomitantright-sidedmazeprocedureatthetimeof
repair.217Thiswasanolderpopulationwithagesrangingfrom9to72years
(median,43years).Thesurgeriesincludedtricuspidvalverepairorreplacement
(n=70),ASDclosure(n=39),andpulmonaryvalveprocedures(n=18).At
hospitaldischarge,83patientswerefreeofAF/flutterand63wereinsinus
rhythm.Follow-upintheearlysurvivorsextendedupto8years(mean,2.7
years).Therewerefourlatedeaths,allfromnoncardiaccauses.Ofthe83known
latesurvivors,77(93%)werefreeofAForflutter.Thus,inpatientswithAFor
flutterassociatedwithcongenitalheartdisease,aconcomitantright-sidedmaze
procedureatthetimeofintracardiacrepairiseffectiveinreducinglaterecurrent
AF/flutter.
ArecentpublicationfromEuropedescribes80consecutivepatients,meanage
39years,withcongenitalheartdiseaseandunresponsiveSVTwhounderwent
surgery.Thesepatientsunderwentintraoperativeablationwithmonopolar
irrigatedRFenergy.218Thisincluded47right-sidedmazeprocedures,and33
Cox–mazeIIIprocedures.In75survivors,theablationwaseffective
immediately.Overanaveragefollow-upperiodof72months,arrhythmias
recurredinonlynine(20%)patientsafterright-sidedmaze,andsix(19%)after
Cox–mazeIII.Intheseadultcongenitalheartdiseasepatients—withahistoryof
preoperativearrhythmiaequaltoorgreaterthan3years(P≤.001),tetralogyof
Fallot(P≤.006),andpreoperativeAF(P≤.016)—therewasoftenrecurrenceof
thearrhythmiaaftersurgicalablation.Conversely,NewYorkHeartAssociation
class3(P≤.047)orbelowwasassociatedwithalowerriskofrecurrence.The
surgicalSVTmanagementstrategywasasafeandeffectiveeveninthiscomplex
population.Freedomfromarrhythmiarecurrencewas75%after6yearsof
follow-upandthelong-termrecurrenceofarrhythmiawasstronglycorrelated
withthelengthofpreoperativearrhythmiaduration.
Anevolutionhasoccurredinsurgicalablationforatrialarrhythmiasand
alternateenergysources,lesionsets,andapproacheshaveevolved,withthe
intentofsimplifyingtheCox–mazeIIIoperationwhilemaintainingsimilar
outcomes.Animpressivestudyof1540patientswhounderwentsurgical
ablationforAFwaspublished,andthoughnotlimitedtocongenitalheart
diseasesurgery,operationswereperformedinconjunctionwithrepairof
congenitalheartdiseasein351(30%)patients.219Theenergysourcesincluded
cutandsewin521(44%),cryothermyin267(22%),RFin262(23%),anda
combinationin139patients(12%).Thelesionsetsincludedbiatriallesionsin
810(68%),isolatedpulmonaryveinlesionsin269(23%),andisolatedleftatrial
lesionsin110(9%).AFablationwasperformedduringisolatedmitralvalve
surgeryin516patients(43%).Themedianfollow-upwas33months(maximum,
20.3years),andlaterhythmfollow-upwasavailablefor80%.Thecut-and-sew
Cox–mazeIIIprocedureofferedsignificantlygreaterfreedomfromAFwithout
antiarrhythmicmedicationscomparedwithalternateenergysourcesandlesion
sets.Althoughalternateenergysourcesoffertheadvantageofquicker
applicationandthepossibilityofminimallyinvasiveapplications,theauthors
concludedthattheCox–mazeIIIoperationwasthereferencestandardforthe
surgicaltreatmentandshouldstillbeconsidered,especiallyforpatientsfor
whomtheablationisofcriticalimportance.
AnytypeofSVTcancomplicatethepostoperativemanagementofcongenital
heartdisease.Ina2014studyofchildrenundergoingcongenitalheartdisease
surgery,approximately44%developedpostoperativearrhythmias.Themost
commonarrhythmiawassupraventricularextrasystoles(65.4%).Riskfactorsfor
supraventricularextrasystoleswererepairofsecundumatrialseptaldefects
(32.3%),ventricularseptaldefects(25%),andtetralogyofFallot(14.7%).220
Atrialarrhythmiasareencounteredfrequentlyaftersurgicalrepairofcongenital
heartdiseasebecausetheseoperationsofteninvolveatrialincisionstoestablish
extracorporealcirculationandapproachtheintracardiacstructures.Together
withstructuralandhemodynamicchangesresultingfromtheunderlyingheart
diseaseandtheuseofinotropicagents,theseatriotomiescreateasubstratefor
atrialtachycardia.Mostcommonly,theearlypostoperativeatrialarrhythmiasare
transientandoftenlesssymptomaticthanVT,althoughinsomepatientsthey
maycausehypotension,heartfailure,orlengthenthehospitalization.Individual
reportstryingtoidentifytheincidenceofearlypostoperativeatrialtachycardia
(otherthanAF)haveshownanincidenceof17%to35%.221,222
Althoughtreatmentstrategiesaremoreofachallengeinthispopulation,the
useofpostoperativeatrialandventriculartemporarypacingwiresallowsfor
improveddiagnosisandcanbeusedtherapeutically.Atrialpacingwiresattached
tothe12-leadECGcanallowtheassessmentoftheatrial/ventricular
relationship.Rapidatrialpacingcanbeusedtoterminateatrialflutterortypical
SVT.Butforrecurrentand/orsustainedSVT,theuseofantiarrhythmicagents
willbeneededatleasttransientlybecauseofthehemodynamicconsequencesof
thesearrhythmias.AsinJET,correctionofelectrolyteabnormalities,anemia,
andvolumestatusandminimizinginotropicagentsmayhelpmanagement.
Intravenousesmololanddiltiazemarereasonableinitialagents,asthesehavea
rapidonsetandcanbeeliminatedfromthesystemrapidlyifineffective.
