Andersons pediatric cardiology 1909

cardiovascularriskfactorscancontributeonlytoaworseoutcome.97


Arrhythmia(seealsoChapter22)
ArrhythmiaisacommonproblemintheFontanpopulation,hasanincreasing
prevalenceinolderpatients,andisoftenassociatedwithFontanfailure.Thetwo
mostfrequentarrhythmiasarebradycardiaduetosinusnodedysfunction,and
atrialflutter.Thelatterismorecorrectlytermedintraatrialreentranttachycardia
(IART).Bothofthesearrhythmiasbecomemoreprevalentwithtimebutarenot
necessarilylinkedtoeachother(Fig.73.10).Inapopulation-basedreport,
bradyarrhythmiasarepresentin7%at10yearsand15%at20yearsafterthe
Fontanprocedure,andtachyarrhythmiain9%and31%,respectively.98
Tachyarrhythmiaiscommonerinthosewithfunctionallimitations,99isomerism,
andanatriopulmonaryFontanconnectionwhencomparedwiththeextracardiac
Fontan.98,100,101Acontemporaryseriessuggestsatrialtachyarrhythmiaispresent
inmostifnotallpatients25yearsaftertheatriopulmonaryFontanprocedure.102
TheextracardiacFontanmayresultinlessIARTthanthelateraltunnel,103
althoughtheevidenceforthisislessconclusive.IARTisalsomorecommon
whenatrioventricularvalverepairorpulmonaryveinsurgeryisrequiredatthe
initialsurgery.100


FIG.73.10 Cumulativeproportionsofarrhythmiasencounteredafterthe
Fontanprocedure.(FromCarinsTA,ShiWY,IyengarAJ,etal.Long-term
outcomesafterfirst-onsetarrhythmiainFontanphysiology.JThorac
CardiovascSurg.2016;152[5]:1355–1363.)

Focal,atrialectopictachycardiasoccurinapproximately13%ofpatientsover
long-termfollow-up,manyinthesamepatientswhohaveIART.103Atrial
fibrillationisbecomingmorefrequentinolderpatients(19%inoneseries)103
withriskfactorsoverlappingthoseoftheagingpopulation(suchasoverweight

andhypertension).
Theoccurrenceofbradyarrhythmiaortachyarrhythmiasignalsa50%to60%
riskofFontanfailureoverthenext10years.98
Ventriculartachycardia(VT)isrelativelyuncommonandusually
asymptomatic,withHolterrecordingssuggestingaprevalenceofapproximately
6%10yearsafterFontan.104However,symptomaticVTorventricular
fibrillationcanoccurinupto3%.10ThepresenceofVTcorrelateswithlarger
ventricularvolumes,104reducedejectionfraction,andmagneticresonance
imaging(MRI)evidenceofmyocardialfibrosis.105
Suddencardiacdeathoccursatlatefollow-upin5%to9%.Riskfactors
includethepresenceofatrialtachyarrhythmia,12atrioventricularvalve
replacementatthetimeoftheFontansurgery,andanimmediatepostoperative
systemicvenouspressuregreaterthan20mmHg.103Preoperativesinusrhythm
isprotective.102

BradycardiaandPacing
Pacemakersmaybeusedinupto25%ofcasesatlatefollow-up,includingthose
implantedforthemanagementofatrialtachycardia.Pacingforbradyarrhythmia
isrequiredinapproximately7%to15%ofpatientsduringlong-termfollow-up.
Inapproximatelytwo-thirds,theindicationissinusbradycardiaand,inonethird,atrioventricularblock.98,106Thelatterismorecommonamongpatients
withcongenitallycorrectedtranspositionofthegreatarteries(Fig.73.11).
PacemakersarecommonlyplacedwhenanatriopulmonaryFontanisconverted
toanextracardiacFontan.Thisprocedureusuallyincludesantiarrhythmia
surgery.Somecenterswillimplantbiatrialantitachycardiapacingdevices
prophylacticallyduringthesameprocedure.107