Andersons pediatric cardiology 1172
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ofleaflettissueiscompartmentedtoproducefewerthanthreecomponentparts,
theleaflettissueitselfremainssuspendedwithinthreeobvioussinuses.
Examinationoftheso-calledunifoliateandunicommissuralvalvefromitsthe
arterialaspect,forexample,usuallyrevealsasolitaryslitlikeopeningwithinthe
valvarcurtain(Fig.44.6A).Carefulexaminationalsorevealsthepresenceof
rapheswithintheskirtofleaflettissue,withexaminationfromtheventricular
siderevealingthepresenceofthreeinterleaflettriangles,albeitwithtwoofthem
beingvestigial.6
FIG.44.6 (A)Featuresofaunifoliateandunicommissuralaorticvalve.(B)
Whenexaminedfromtheventricularaspect,vestigialinterleaflettriangles
arepresentbeneaththeraphesintheapparentlyunifoliatevalvarcurtain,
withonlyonesuchtriangleshowninthedrawing.Onlytheperipheralend
ofthesolitaryzoneofappositionistetheredatthesinutubularjunction
(star).(CourtesyBensonR.Wilcox.)
Similarly,examinationofthemajorityofthevalvesshowingabifoliate
patternoftheleaflets(Fig.44.7)revealsthattheyareformedwithinatrisinuate
prototype.8,9
FIG.44.7 Bifoliateaorticvalves.(A)Raphebetweentheconjoinedleaflet
guardingthetwoaorticsinuses.Notethefailureofformationofthe
interleaflettrianglebeneaththeraphe,withonlytwointerleaflettriangles
extendingtothesinutubularjunction(arrows).(B)Bifoliatevalvewiththe
conjoinedleafletformedbetweentheleafletsguardingtherightcoronary
andnoncoronarysinuses.Inthisinstance,themembranousseptumis
foundbeneaththevestigialinterleaflettriangle.Onlytheinterleaflet
trianglesboundingtheleftcoronaryaorticleafletextenttothesinutubular
junction.
Intheunifoliate,orunicommissural,valve(typicallyseenininfantswithsocalledcriticalstenosis),itfollowsthatthekeyholeopeningwithinthevalvar
curtainrepresentstheonlyproperlydevelopedzoneofapposition(seeFig.44.6).
Itisfoundbetweenthehingesoftheleftandnoncoronaryaorticleafletsand
“points”towardthemitralvalve.Becauseofthevestigialnatureoftheputative
zonesofappositionbetweentheotherleaflets,theyareabnormallyattachedto
theventricularwallinannularfashion.Thereforeitisparadoxicthatvalvar
leafletspossessingaring-likeattachmentarelikelytobestenoticorregurgitant.
Whenseeninpathologicarchives,theunicuspidandunicommissuralvalvesare
oftenhousedinsmallfibroelastoticleftventricles,theheartsthemselves
fulfillingmanyoftheanatomiccriterionsforinclusionwithinthehypoplastic
leftheartsyndrome(seeChapter69).
Thebifoliateaorticvalveisalsooftendescribedinassociationwithcritical
aorticstenosis,albeitagainformedonatrisinuateprototype,10butisalsofound
inasymptomaticindividuals.Theleafletsthemselvesguardmarkedlydissimilar
partsofthevalvarorifice,withthelargerleafletformedbyfusionoftwo
putativeleaflets,typicallywitharapheshowingthelineofnonseparation
betweenthem(seeFig.44.7).Theconjoinedleafletusuallyrepresentseither
fusionofthetwocoronaryleaflets(seeFig.44.7)orfusionoftherightand
noncoronaryleaflets.Trulybisinuateandbifoliatevalvesdoexistbutarerare,as
aretrisinuatebutbifoliatevalveswithoutevidenceofaraphebetweenthe
presumedconjoinedleaflets.9Stenosis,whenitoccurs,istheresultoffusionof
theendsofthezoneofappositionbetweenthetwoleaflets.Bifoliatevalvescan
alsoproduceproblemswhentheybecomeincompetentduetoprolapseorifthey
provideanidusforendocarditis.Thisismorelikelytooccurinadultlifeandis
rarelyseeninchildhood.Stenosisproducingproblemsinchildhoodcanalsobe
seeninthesettingofatrifoliatevalve,butmoreusuallysuchvalvesaretheseat
ofsenileaorticcalcification.11Whenseeninchildhood,thetrifoliatevalve,with
dysplasticleaflets,isencounteredmostfrequentlyininfants.Astenotictrifoliate
valveisrareinolderchildrenandadolescentsunlesstheyhaveundergone
previoussurgery.
Calcificationoftheaorticvalvecandevelopfromthethirddecadeinall
patientswithmildlystenoticorbifoliatevalves.Itmaystartasearlyasthe
seconddecade,particularlyifthevalvesaredysplasticandmyxomatous.
However,mostpatientspresentinlaterlifewithseverecalcificaorticstenosisin
whatwasinitiallynomorethanamildlystenosedvalveoravalvewithleaflets
initiallyofmarkedlydissimilarsize.12Thechangesaremorecommoninmales
thanfemales.Patientswithfamilialhypocholesterolemia,progeria,andrickets
developcalcificationearlier,eveniftheaorticvalveisonlymildlyabnormal.
Patientswithbifoliatevalvesproducingminimalstenosisusuallydonotdevelop
calcificstenosisuntilthesixthorseventhdecade,butpresenceofmoderateor
severestenosisinchildhoodcanleadtoquiteheavycalcificationinthethirdand
fourthdecades.
SubvalvarStenosis
Avarietyoflesionscanobstructthesubaorticoutflowtract,withorwithouta
coexistingventricularseptaldefect.Whenthereisaninterventricular
communication,posterocaudaldeviationofthemuscularoutletseptumisusually
themostimportantlesion.Thislesionisdiscussedinthechaptersdevotedto
ventricularseptaldefectandinterruptionoftheaorticarch.Obstructioncanalso
beproducedbyhypertrophyoftheventricularseptum,asseeninhypertrophic
cardiomyopathy(Chapter61),byanomaloustissuetagsderivedfromthe
membranousseptumortheleafletsoftheatrioventricularvalvesorby
