Andersons pediatric cardiology 1313
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atrialseptum,acurvedconfigurationoftheventricularseptum,andunusual
arterialrelationshipsforthegivenpathology(seeFigs.49.19and49.20).The
ventricularinletstypicallyadoptasuperoinferiorrelationship,withtheapical
componentsshowingthemostunusualrelationships.Inextremeforms,the
ventricularapicesaredisplacedtotheoppositeside,andshowareversedsideby-siderelationship.Thiscanoccurwithanyknowncombinationofconnections
ofthecardiacsegments.Twistingisusuallyinsuchadirectiontoplacetheright
ventricularinletanteriorandsuperiortotheleftventricularinlet.Incongenitally
correctedtranspositionwithusualatrialarrangement,forexample,andasshown
inFig.49.15,themorphologicallyleftventricleisusuallyaright-sidedstructure,
whiletheaorticvalvemostfrequentlyislocatedanteriorlyandtotheleft.The
ventricularmassinthepresenceofthecriss-crossmalformationistwisted
counterclockwiseinsuchawaythatthemorphologicallyrightventricularinlet
achievesarightwardandsupero-anteriorpositionrelativetotheleftventricular
inlet(seeFig.49.19).Theaorticvalveispositionedanteriorlyandcanberightsided.Inthepresenceofusualatrialarrangement,ofcourse,aright-sidedand
anterioraortaarisingfromaright-sidedmorphologicallyrightventricleismore
typicallyfoundwiththesegmentalcombinationsof“simple”transposition(see
Chapter37).Nonetheless,twistingcanalsooccurwiththeconnectionsofthe
segmentsthatnormallyproducetheusualvariantoftransposition.The
ventricularmassistwistedclockwise,givingthespuriousimpressionof
congenitallycorrectedtransposition(seeFigs.49.14and49.20).Oncethe
investigatorisawareofthepossibility,boththeabnormalrelationshipsandthe
truesegmentalconnectionsarereadilydemonstratedbycurrenttechniquesfor
imaging(seeFig.49.18).Thekeyisfirsttoanalyzetheconnectionsbetweenthe
cardiacsegments,andonlythentotakenoteoftherelationsoftheventriclesand
arterialtrunks.Thesecretisnottobesurprisedwhentherelationshipsobserved
arenotasanticipatedforthedemonstratedsegmentalconnections.
FIG.49.18 Magneticresonanceimagesfromapatientwithconcordant
atrioventricularconnections,withtheatriums(RA,LA)connectedtotheir
appropriateventricles(RV,LV),andshowingthecrossingofthe
atrioventricularinlets(arrows).Thisistheessenceoftheso-calledcrisscrossheart,theright-sidedlocationofthemorphologicallyleftventricle
relativetotherightventriclegivingthespuriousimpressionofthe
discordantatrioventricularconnections.Comparewiththereconstruction
showninFig.49.14.
FIG.49.19 Reconstructionsmadefromcomputedtomographicdatasets
comparethearrangementusuallyfoundincongenitallycorrected
transposition,wheretheaortaandmorphologicallyrightventricleare
usuallyleft-sided(upperpanels),withthesituationproducedbytwistingof
theatrioventricularconnections(lowerpanels).
FIG.49.20 Reconstructionspreparedfromcomputedtomographic
datasetscomparetheeffectoftwistingoftheatrioventricularconnections
(lowerpanels)withtheusualarrangementfoundintranspositionwith
concordantatrioventricularconnections(upperpanels).
Inthetypicalsituationofthecriss-crossheart,irrespectiveofthe
combinationsofatrioventricularandventriculoarterialconnections,the
ventriculartopologyisasanticipatedfortheidentifiedatrioventricular
connections.Thus,intheillustratedsituationwithconcordantatrioventricular
connections(seeFig.49.14),althoughthemorphologicallyleftventricleisrightsideddespitetheusualatrialarrangementoftheatrialchambers,the
morphologicallyrightventriclewillacceptonlythepalmarsurfaceoftheright
handoftheobserverwiththethumb,figurativelyspeaking,inthetricuspid
valve.Inotherwords,thereisretentionofright-handventriculartopology
despitetherotationoftheventricularmassalongitslongaxis.Insomeveryrare
