Andersons pediatric cardiology 1809
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FIG.69.9 Aneurysmalflooroftheintactovalfossaasseenfromtheright
atrialaspect.Afour-chambersectionoftheheartisshowninatrightinFig.
69.7.
Insomeofthesepatientswithanintactovalfossa,thepulmonaryvenous
drainagecanbeabnormalbecauseofthepresenceofaso-calledlevoatrial
cardinalveinorbecauseoffenestrationofthewallsthatusuallyseparatetheleft
atriumfromthecavityofthecoronarysinus.Thisprovidesanoverflowforthe
leftatrialreturn.Moreusually,thereisnosuchoverflowwhentheatrialseptum
isintact.Theresultingincreaseinleftatrialpressureproducesincreasedleft
atrialhypertrophy,alongwithchangesinthelungs,includingarterializationof
thepulmonaryveinsandlymphangiectasia,witha“cobblestone”appearanceof
thepulmonarysurfacesseenatautopsy.Thesearebadprognosticfeatures.In
mostinstances,asstated,theovalforamenispatentanddoesnotobstructflow
fromlefttoright.Theprimaryatrialseptumisfrequentlydeviatedintotheleft
atrium.Leftventricularendocardialfibroelastosisisseenonlywhenthemitral
valveisperforate.Aorticatresia,whenpresent,canresultfromanimperforate
valve.Moreusually,thereisnoevidenceofpersistingleafletsatthe
ventriculoarterialjunction,withfibromusculartissueinterposingbetweenthe
ventricularcavityandtheblind-endingaorticroot.Theaorticrootitselfis
usuallymarkedlyhypoplastic,withtheascendingaortaservingonlyasaconduit
tofeedthecoronaryarteries(Fig.69.10).13Furtherdistally,aorticcoarctationis
common,occurringinoverfour-fifthsofpatients.14Theobstructiveshelfis
typicallyinapreductallocationbutcanbefoundparaductally.Ductaltissueis
notonlyincorporatedintothestenosingshelfbutalsomayextendproximally
anddistally,animportantpointforthoseundertakingsurgicalpalliationofthese
patients.Abnormalitiesofthecoronaryarteries,suchasventriculocoronary
fistulasandabnormaltortuosity,aremorecommoninthesubgroupofpatients
withmitralstenosisandaorticatresia(Fig.69.11).Suchcoronaryarterial
fistulas,ifpresent,arenotnecessarilyassociatedwithabnormalitiesoftheright
ventricularmyocardiumbutcanproduceanincreasedriskofmortalityatthe
firststageofaNorwoodreconstruction.15Theconductiontissuesareintheir
expectedlocation,albeitwithminiaturizationoftheleftbundlebranchin
keepingwiththesizeoftheleftventricle.
FIG.69.10 Typicalarrangementofthearterialpathwaysinthesettingof
hypoplasticleftheartsyndrome.Thepulmonarytrunkfeedsthedescending
aortaviathepersistentlypatentarterialductandprovidesretrogradeflow
totheminuteascendingaorta,whichservesasaconduittofeedthe
coronaryarteries.
