Andersons pediatric cardiology 806

Figs.31.19Cand31.21).Theperimembranousventricularseptaldefectopening
totheinletoftherightventriclewillalsodemonstratelackofoffsettingbetween
theatrioventricularvalves(seeChapter32).Hencethetrifoliatenatureoftheleft
atrioventricularvalve,alongwiththegooseneckappearanceoftheleft
ventricularoutflowtract,distinguishestheatrioventricularseptaldefectinthis
settingfromthatoftheperimembranousinletventricularseptaldefect.Rarelya
leftatrioventricularvalvewiththreeleafletsmaybetheonlymanifestationof
patientshavinganatrioventricularseptaldefectwithacommonatrioventricular
junction,theatrialandventricularseptalstructuresbeingintact.Suchpatients
maywellpresentashaving“mitral”regurgitation,withthetruenatureoftheir
spontaneouslyclosedatrioventricularseptaldefectnotinitiallybeingrecognized.
Thediagnosticechocardiographichallmarks,however,arethesameasforthe
otherformsofatrioventricularseptaldefect.5,52Otherlesscommonvariants
foundwithseparateatrioventricularvalvarorifices,suchascommonatriumand
so-calleddouble-outletleftorrightatrium,areeasilyrecognizedinacomplete
echocardiographicexamination.


FIG.31.19 Apicalfour-chamberplaneinsystoledemonstratehowthe
relationshipofthecommonatrioventricularvalvehelpstodeterminethe
degreeofatrial-and/orventricular-levelshunting.(A)Thecommon
atrioventricularvalveisfirmlyattachedtothecrestofthemuscular
ventricularseptumwithexclusivelyatrial-levelshunting,theso-called
partialatrioventricularseptaldefect.(B)Thecommonatrioventricularvalve
againappearstobeattachedtothecrestofthemuscularventricular
septum,withlargeatrial-levelshunting;however,inthetwo-dimensional
viewthereissuggestionofpossibleventricular-levelshunting,theso-called
transitionaldefect,whichwouldneedtobeinterrogatedbycolorDoppler.
(C)Thecommonatrioventricularvalveisfirmlyattachedtotheleading
edgeoftheprimaryatrialseptumwithexclusivelyventricular-level
shunting.Thecommonatrioventricularvalvewouldbepartitionedintotwo

separatevalveorifices.(D)Thecommonatrioventricularvalveresides
approximatelymidwaybetweentheleadingedgeoftheprimaryatrial
septumandthecrestofthemuscularventricularseptum,withsignificant
atrial-andventricular-levelshunting,theso-calledcompletedefect.la,Left
atrium;lv,leftventricle;ra,rightatrium;rv,rightventricle.


FIG.31.20 Subcostalparacoronalechocardiographictwo-dimensional(A)
andcolorDoppler(B)imagesdemonstratinganatrioventricularseptal
defectwithexclusivelyatrial-levelshunting.Theatrialcomponentofthe
defectisprofiledwellinthisplane.la,Leftatrium;lv,leftventricle;ra,right
atrium.

FIG.31.21 imagesfromapatientwithanatrioventricularseptaldefect
withseparateatrioventricularvalveorificesandanintactatrialseptum.(A)
Attachmentofthecommonatrioventricularvalvetotheleadingedgeofthe
primaryatrialseptum,partitioningthevalveintotwoeffectiveorificesand
allowingexclusivelyventricularshuntingwithlackofoffsettingofthe
atrioventricularvalves.(B)Subcostalshort-axisplaneimagedemonstrating
theseparateatrioventricularvalvarorificesofthecommonjunction,
separatedbybridgingtissue.Thethreeleafletsarebestvisualizedina
slightlyangulatedparacoronalplane.ibl,Inferiorbridgingleaflet;la,left
atrium;lv,leftventricle;ml,muralleaflet;rv,rightventricle;rvot,right
ventricularoutflowtract;sbl,superiorbridgingleaflet.