Andersons pediatric cardiology 1910
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FIG.73.11 (A)ECGdemonstratingpreoperativesinusrhythmina7-yearoldfemalewithcongenitallycorrectedtranspositionofthegreatarteries
andhypoplasticleftventriclewhounderwentanextracardiacconduit
Fontanwithtricuspidvalvuloplasty.(B)PostoperativeECGofthesame
patientdemonstratinghigh-gradeAVblockwithjunctionalescapebeats.
NoteintermittentlyconductedPwaves(redarrows).
BradyarrhythmiaismorecommonaftertheatriopulmonaryFontanthanthe
lateraltunnelorexternalcardiacconduit(Fig.73.12).Heartratevariability,a
subtlemarkerofsinusnodedysfunction,isreducedinlateraltunnelandexternal
conduitFontaninequalmeasurewhencomparedwithhealthycontrols.108There
issomesuggestionthattheexternalconduitmaybeassociatedwithmoresinus
nodedysfunctionthanthelateraltunnel,9,109butthisisnotaconsistent
finding.106Sinusnodedysfunctionmayrelatemoretothenatureoftheprior
superiorvenacavapulmonaryanastomosis(aswellasnativesinusnode
function)becausethatsurgeryisclosetothesinusnodeandsinusnodeartery.109
Atrialpacing,whichusuallymustbeepicardialandmayrequireextensive
thoracicsurgerytobeachieved,isgenerallyreservedforthosewithsymptomatic
chronotropicincompetence.Dependingontheanatomy,itmaybefeasibleto
placetransvenousatrialleads;however,itisnotunusualtohavetoplaceleadsin
nonstandardpositionsbecauseareasofviablemyocardialtissuecanbelimited
(Fig.73.13).
FIG.73.12 Sinusbradycardiaandjunctionalrhythminanasymptomatic
33-year-oldmalewithanatriopulmonaryFontan.
FIG.73.13 Chestradiographyofa53-year-oldfemalewithtricuspid
atresiawhounderwentamodifiedFontanwithrightatrium(RA)toright
ventricle(RV)valvedconduitandrequiredtransvenousatrialpacing.Note
thelowpositionoftheatriallead.Itisnotunusualtohavetoplaceleadsin
uncommonpositionsintheFontanpopulationsinceareasofviable
myocardialtissuecanbelimited.AMelodyvalvehasbeenplacedinthe
RAtoRVconduit.
Ventricularpacingshouldbeavoidedorminimizedasfaraspossiblebecause
oftheriskofcausingventriculardyssynchronyandpacemaker-induced
cardiomyopathy,cardiacfailure,andatrioventricularvalveregurgitation.109
Fontanpatientswithventricularpacinghaveafivefoldriskoftransplantordeath
comparedwithmatchednonpacedcontrols.110Thevalueofcardiac
resynchronizationtherapyisbeingexplored;resultsaregenerallydisappointing,
buttheremaybeaplaceinspecificcasessuchaspostpacingcardiomyopathyor
whenthereisasystemicleftventricleandleftbundlebranchblock(Fig.73.14).
