Andersons pediatric cardiology 73
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FIG.2.13 Heartsectionedalongitsshortaxisthroughthemiddleofthe
ovalfossa(redbar)andphotographedfromabove.Inthisheart,theoval
foramenremainsprobepatent.Theflapvalveisanchoredontheleftatrial
aspect,withtheinferiorhornshowninthissection,buttheforamen
remainspatentbecausetheflapvalveisnotfusedtotheleftaspectofthe
anterosuperiorinteratrialfold.
MorphologicallyRightVentricle
Themuscularwallsoftherightventricleextendfromthediscrete
atrioventricularjunctiontotheirunionwiththefibroelasticwallsofthe
pulmonarytrunkattheanatomicventriculoarterialjunction.Thecavitythus
demarcatedhasthreecomponents:theinlet,theapicaltrabecularpart,andthe
outlet(Fig.2.14).
FIG.2.14 Rightventricleopenedbyremovingitsanteriorwall,showing
howthecavityextendsfromtheatrioventricularjunction(blackdottedline)
totheventriculoarterialjunction(greendottedline).Thecavitythus
demarcatedhasinlet,apicaltrabecular,andoutletcomponents.
Theinletcomponentsurroundstheleafletsofthetricuspidvalve,extendingto
theattachmentsofthevalvartensionapparatus.Thethreeleafletsofthevalve
takeoriginfromtheseptal,inferiorormural,andanterosuperiormarginsofthe
atrioventricularjunction(Fig.2.15).
FIG.2.15 Multidetector-rowcomputedtomographicdatasetsegmented
andreconstructedtoshowthelocationsoftheleafletsofthe
atrioventricularvalveinattitudinallyappropriatefashion,withthesection
takeninleftanteriorobliqueorientation.Notethesolitaryzoneof
appositionbetweentheleafletsofthemitralvalve.
Theseptalleaflethasmultiplecordalattachmentstotheseptum.Theinferior
leafletrunsalongthediaphragmaticsurfaceoftheventricle.Itsmarginwiththe
anterosuperiorleafletisoftenindistinct,butitspatternofclosurerevealsthe
trifoliateconfigurationofthevalve.8Theanterosuperiorleafletisthemost
extensiveofthethree.Itextendsfromitszoneofappositionwiththeseptal
leaflet,anareasupportedbythemedialpapillarymuscle,totheacutemarginof
theventricle.Theprominentanteriorpapillarymusclearisesfromthe
septomarginaltrabeculationtosupportthisleaflet,butnotalwaysatitssiteof
appositionwiththeinferiorleaflet.
Theapicalpartoftheventriclehasparticularlycoarsetrabeculations,this
beingthemostconstantfeatureoftheventricleinmalformedhearts.Oneof
thesetrabeculationsontheseptalsurface,theseptomarginaltrabeculation,is
particularlyprominent.Itdivergesintotwolimbsatthebase,whichclaspthe
supraventricularcrest,alsoknownastheseptalband(Fig.2.16).
