Andersons pediatric cardiology 60
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FIG.1.18 Someofthepotentialuniventricularatrioventricular
connections.Inreality,thesecanexistwithanyarrangementoftheatrial
appendages(top),withdouble-inlet,absentright,orabsentleft
atrioventricular(AV)connections(middle),andwithdominantleftventricle
(LV)orrightventricle(RV),orsolitaryandindeterminateventricle(bottom).
Themiddleandbottomrowsareillustratedwithusualarrangementofthe
atrialappendagessimplyforconvenience.Thereisfurthervariabilitywith
regardtothepositionoftheincompleteventricle,andwithventriculoarterial
connections,andsoon.Theseheartsthereforeexemplifytheneedforfull
sequentialsegmentalanalysisanddescription.
Thereforeventricularmorphologymustalwaysbedescribedseparatelyin
thoseheartsinwhichtheatrialchambersarejoinedtoonlyoneventricle.In
thesehearts,althoughonlyoneventricleisjoinedtotheatriums,asecond
ventricleispresentinmostofthem.Thissecondventricle,ofnecessity
incomplete,willbeofcomplementarytrabecularpatterntothedominant
ventricle.Mostfrequently,thedominantventricleisaleftventricle.The
incompleteventriclepossessesrightventricularapicaltrabeculations.More
rarely,thedominantventricleismorphologicallyright,withtheincomplete
ventriclebeingmorphologicallyleft.Evenmorerarely,heartswillbefoundwith
asolitaryventricularchamberofindeterminatemorphology(seeFig.1.6).In
clinicalpractice,seeminglysolitaryleftorrightventriclesmaybeencountered
whenthecomplementaryincompleteventricleistoosmalltobedemonstrated.
ArrangementsoftheAtrioventricular
Valves
Describingthefashioninwhichtheatriumsarejoinedtotheventriclesacross
theatrioventricularjunctionsaccountsonlyforthewayinwhichtheatrial
musculatureinsertsintothebaseoftheventricularmass.Themorphologyofthe
valvesguardingtheoverallatrioventricularjunctionalareaisindependentofthis
feature,withintheconstraintsimposedbythepatternofthejunctionsitself.
Whenthecavitiesofbothatriumsarejoineddirectlytotheventricularmass,the
right-andleft-sidedatrioventricularjunctionsmaybeguardedbytwopatent
valves(seeFig.1.11),byonepatentvalveandoneimperforatevalve(seeFig.
1.13),byacommonvalve(seeFig.1.12),orbystraddlingandoverridingvalves
(Fig.1.19).
FIG.1.19 Influenceofanoverridingatrioventricular(AV)junctiononthe
precisearrangementoftheconnections.Whenthelesserpartofthe
overridingjunctionisattachedtothedominantventricle,theconnections
areeffectivelybiventricularandconcordantintheexampleshownatleft.In
contrast,whenthelesserpartiscommittedtotheincompleteventricle,the
connectioniseffectivelydoubleinletandtotheleftventricleinthe
illustration(right).Anycombinationofatrialchambersandventriclescanbe
foundwithsuchstraddlingandoverridingvalves.
Thesearrangementsofthevalvescanbefoundwithconcordant,discordant,
biventricularandmixed,ordouble-inlettypesofconnection.Eithertheright-or
left-sidedvalvemaybeimperforate,producingatresiabutinthesettingofa
