Andersons pediatric cardiology 1109

FIG.42.3 Idealizedarrangementofthepulmonaryvalvarleafletsasseen
fromthearterialaspect.Thefreeedgeofeachleafletislongerthanthe
cordofthesinussupportingit,permittingtheleafletstoclosesnuglyalong
theirzonesofapposition(arrows).Thezonesofappositionareattached
peripherallyatthesinutubularjunction(stars),withtheseareasdescribed
asthevalvarcommissures.Whenclosed,theymeetatthevalvarcentroid
(redcircle).

Fusionoftheadjacentleafletsalongtheirzonesofappositionistheessenceof
valvarstenosis.Thefusionistypicallyuniform,sothatthevalvarorificeis
narrowedtoacentralopening.Themorethefusionextendstowardthecenterof
thevalve,thenarrowerwillbethecentralopeningandthemoreseverewillbe
thevalvarstenosis.Whenthestenosisismildtomoderate,theopeningwillhave
atriangularconfiguration(Fig.42.4).


FIG.42.4 Thismoderatelystenoticvalveisshownwiththepulmonary
trunkremoved,permittingthespecimentobephotographedfromthe
arterialaspect.Thezonesofappositionoftheleafletsarefusedfromtheir
peripheralattachments(stars)towardthecentroidofthevalvarorifice
(arrows).Thisproducesanarrowedcentralorifice.Notethetetheringofthe
leafletsatthesinutubularjunction.

Incontrast,inthemostsevereformsofstenosis,whichproducethetypical
criticalarrangementseeninneonates,theextentoffusionissufficienttoleave
onlyacentralpin-sizedopening.Inthisso-calleddomedstenosis,thecentral
partofthecupolatendstobesmooth,withevidenceofthefusedzonesof
appositionseentovaryingdegreesasperipheralraphes,withtetheringatthe
sinutubularjunction(Fig.42.5).

FIG.42.5 Inthiscriticallystenoticvalve,thevalvarcupolaissmooth,with
evidenceofthefusedzonesofappositionseenonlyatthemarginsofthe
valve.

Openingthecriticallystenoticvalveshowsthat,becauseoftheobliterationof
thezonesofappositionbetweentheleaflets,theextentoftheirsemilunar
hingingisreduced.Becauseofthis,theirlineofattachmentwithinthe
pulmonaryroothasamorecircularconfiguration(Fig.42.6).

FIG.42.6 Left,Viewofacriticallystenoticvalveasseenfromthearterial