Andersons pediatric cardiology 1149
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BecausethesizeofthetricuspidvalveparallelsthediminishingRVcavity,
measurementofthevalveservesasareasonablygoodguidetothevolumeofthe
hypoplasticventricularcavity.35,36Thetricuspidvalvarapparatusitselfshows
varyingdegreesofmalformationinmostcases.Dysplasiaoftheleafletsis
commonbutdoesnotcorrelatewiththesizeofthecavity.Ebsteinmalformation
isthemostcommonabnormality.Ebsteinmalformation,orseverevalvar
dysplasia,isaubiquitousfindingincaseswithdilatedventricles,butfailureof
fulldelaminationoftheseptalleafletscanalsobefoundwhenthecavityis
hypoplastic(Fig.43.7).
FIG.43.7 Heartwithobliterationoftheapicalcomponentandhypoplasia
oftheoutletcomponent.ThetricuspidvalveshowsevidenceofEbstein
malformation,withtheseptalleaflethingedawayfromtheatrioventricular
junction.
Exaggeratedpersistenceofthevalvesofthesystemicvenoussinusisalsoa
frequentfindinginheartswithventricularcavitaryhypoplasia.Adeficiencyof
theflooroftheovalforamen,orpatencyoftheforamen,isauniversalfinding.
Thepulmonarytrunkisusuallymildlyhypoplasticorofnormalsize(Fig.43.8,
left).Onoccasion,itmaybesmall,orevennomorethanathreadlikesolidcord
(seeFig.43.8,right).
FIG.43.8 Variabilityindimensionsofthepulmonarytrunk.Usuallyitisno
morethanmildlyhypoplastic(left),butitcanrarelybeligamentous(right).
Inbothinstances,pulmonaryarterialsupplyisthroughthepersistently
patentarterialduct.
Thedimensionsofthepulmonarytrunkshownocorrelationwiththesizeof
therightventricularcavity.EventhosewithatinyRVcanhaveapulmonary
trunkofnear-normalsize.Almostalwaysthepulmonaryarteriesarefedthrough
apersistentlypatentarterialduct.Shouldsystemic-to-pulmonaryarteriesbe
encountered,thesuspicionshouldberaisedthatinitiallytherewasan
interventricularcommunication,butthattheholebetweentheventriclesclosed
duringfetallife.
WithDilatedRightVentricularCavity
Patientswithdilatedcavities,alongwiththosehavingRV-dependent
circulations,presentthegreatestproblemsintreatmentandhavetheworst
prognosis.Thedilationofthecavityoccursduringfetallife,sowhenthepatients
presentatbirth,theheartfillstheentiretyofthethoraciccavity,producingthe
“wall-to-wall”heart(Fig.43.9,top).1Significanttricuspidregurgitationis
presentinmostofthesecases.
FIG.43.9 Top,Typical“wall-to-wall”heart(arrow).Thelungsarenotseen,
