Andersons pediatric cardiology 770
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FIG.29.8 Featuresofthesinusvenosusdefect.(A)Theusualvariant,in
whichtheorificesofthesuperiorcavalvein(SCV)overridestherimofthe
ovalfossa,itselfdeficientinthisheart.Aprobehasbeenplacedthrough
thetubeofextracavitarytissueenclosedwiththesuperiorrim(seeFig.
29.9).(B)Themoreunusualvariant,inwhichthedefectiswithintheorifice
oftheSCV.Inbothinstances,thekeyfeaturearetheanomalous
connectionsoftherightpulmonaryveins.
Insomeinstancesthereisnooverridingoftheorificeofthesuperiorcaval
vein(seeFig.29.8,right).Despitethenormalattachmentofthecavalveintothe
rightatrium,theanomalousattachmentoftherightpulmonaryveinsstillcreates
theinteratrialcommunicationoutsidetheconfinesoftheintactatrialseptum.
Thereforethephenotypicfeatureofthelesionsistheanomalousattachmentof
oneormorepulmonaryveinstoasystemicvein,withthepulmonaryveins
retainingtheirleftatrialconnection(Fig.29.9).10
FIG.29.9 Phenotypicfeatureofthesinusvenosusdefect,namelythe
anomalousattachmentofarightpulmonaryveintoasystemicvenous
channel,inthisexampletothesuperiorcavalvein(SCV),whilethe
pulmonaryveinretainsitsleftatrialconnection.Thepresenceofthe
extraseptalcommunicationthusturnsthesuperiorinteratrialfoldintoatube
containingfibroadiposetissue(alsoseeFig.29.8).
Inthissettingthesuperiorrimofthefossabecomesamusculartubeenclosing
acorridorofextracardiacfat.Aprobecanbepassedfrombacktofrontthrough
thetubewithoutencroachingontheatrialcavities(seeFig.29.8,left).The
presenceofasuperiorsinusvenosusdefectdoesnotmarkedlyaffectthesiteof
thesinusnode,whichisfoundlateraltothesuperiorcavoatrialjunction,lying
immediatelysubepicardiallywithintheterminalgroove.Thusapatchplaced
withintheatriumtoreconnectthecavalveintotherightsideshouldnot
jeopardizethesinusnode.Inferiorsinusvenosusdefectsarefarlesscommon.
Theytooareassociatedwithananomalousattachmentoftherightpulmonary
veins,butinthesecasestheanomalousattachmentoftherightinferior
pulmonaryveincreatestheextracardiacconduit.Closureofsuchadefectshould
notjeopardizeeitherthesinusortheatrioventricularnode.Inferiorsinusvenosus
defectsmust,nonetheless,bedistinguishedfromdefectswithintheovalfossa
thatextendtothemouthoftheinferiorcavalvein(seeFig.29.6,right).Ifthe
middlerightpulmonaryveinisanomalouslyconnectedtotherightatriumwhile
retainingitsleftatrialconnection,thesinusvenosusdefectcandraintothe
middlepartofthesmooth-walledsystemicvenouscomponentoftherightatrium
(Fig.29.10).
FIG.29.10 Inthisheart,themiddleandinferiorrightpulmonaryveinsare
anomalouslyconnectedtothesystemicvenouscomponentoftheright
atriumwhileretainingtheirleftatrialconnections.Thesinusvenosusdefect
islocatedmidwaybetweentheorificesofthesuperiorandinferiorcaval
veins.Thereisalsoapersistentleftsuperiorcavalveindrainingtotheright
atriumthroughtheenlargedmouthofthecoronarysinus.
CoronarySinusDefects
Intheabsenceofthewallsthatusuallyseparatethesinusfromtheleftatrium,
therightatrialorificeofthesinusbecomesaninteratrialcommunication(Fig.
29.11).11
