Andersons pediatric cardiology 820
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areaofthetwoorificesshouldbeaslargeastheareaoftheorificeofthenormal
mitralvalveforapatientofcomparablebodysurfaceareabutwithoutan
atrioventricularseptaldefect.Thishypothesisresultsinthefollowingformula:
FIG.31.60 Creationofdualorificeswithintheleftatrioventricularvalve
usingacentralpledgetedstitch.Theapexofthemuralleafletissuturedto
theendofthezoneofappositionbetweentheleftventricularcomponents
ofthebridgingleaflets.Thetwoorificesshouldbemeasured,andtheir
combinedareashouldnotbelessthanZ−2forbodysurfacearea.
withD1andD2representingthediametersofthetwoorificesanda
nomogram(Fig.31.61)thatcanbeusedintheoperatingtheatersoastoavoid
stenosis.Long-termresults,however,arelacking.Anincreaseinfrictional
energylossbythelargercircumferenceinthesettingofequalsurfaceareaof
twoorificesinsteadofoneisconsciouslyneglectedinthissimpleequation.
FIG.31.61 Thediametersoftwoseparateorificescanbeconvertedtothe
equivalentdiameterofasingleorifice.Whenthediameterofoneorificeis
indicatedintheleadingcolumnandthediameteroftheotherorificeinthe
leadingrow,theircombinedareascanbefoundattheintersectionof
columnandrow.
Reoperation
Reoperativesurgeryforleftatrioventricularvalvarregurgitation,orrarely
stenosis,differsinitspossibilitiesandrisksascomparedwithreoperationonthe
mitralvalve.Thepossibilitiesforrepairaresomewhatlargerinthatazoneof
appositionthatisnotclosedfullycaneasilybesuturedtoabolishregurgitation.
Theedgesareusuallyverysturdybecausetheyareextremelyfibrosed,which
facilitatesclosure.Tissueadvancementcanalleviateacentralshortageofvalvar
tissues.85,86Additionalleafletaugmentationandusageofartificialcordshas
beendescribedandisapromisingtechnique.87Ifrepairfailsandthevalvehasto
bereplaced,caremustbetakennottocreateobstructionwithintheleft
ventricularoutflowtract.Itiswisetoresecttheinferiorwalloftheoutflowtract
withtheaidofadentalmirrorsoastoabolishanypossibleobstructionwhileat
thesametimeavoidingdamagetotheaorticvalve.23,88
SurgeryforDualOrificesintheLeft
AtrioventricularValve
Dualorificesintheleftorrightventricularcomponentsoftheatrioventricular
valveoccurinabout5%ofpatients,moreofteninthesettingofseparateleftand
rightvalvarorifices.88Althoughrecognitionisdifficult,suchvalveswithdual
orificescanbesuspectedusingpreoperativeechocardiography.88Theadditional
orificeisusuallynotregurgitant.Shouldtheabnormalconnectionbetween
leafletsbesevered,joiningtogetherthetwoorifices,catastrophicregurgitationis
certaintoensue.Consequentlythepossibilitiesforsurgicalrepairofthesevalves
arelimited.Anyannuloplastywillreduceevenfurthertheeffectiveareaofthe
valvarorifice.Theneedtoreplacethesevalves,therefore,issubstantiallygreater
thanthatfortheusualtrifoliateleftvalvewithasingleorifice.Ifpossible,these
extraorificesarebestleftalone.89
AssociationWithTetralogyofFallot
Therelativepaucityofpapersonclinicalresultsdescribingtherepairofthe
combinationofatrioventricularseptaldefectandtetralogyofFallotisnotin
keepingwiththereportedincidenceofthiscombination,whichissaidtobe
presentinabout5%ofallpatientswithatrioventricularseptaldefect.Papersof
substancedescribeexperienceinextremelysmallseries,althoughsomelarger
serieshaveappeared.90,93,94Thispaucityofreportsmightbeexplainedby
publicationbiasorbytheselectionofpatients.Publicationbiascouldplayarole
whentheresultsmakecliniciansdisinclinedtopublish.Selectionofpatients
couldalsoplayarolewhenoperationisdeemedunsuitablebecauseofnatural
palliation,withthepulmonarystenosiscounterbalancingthepotentialshuntin
thesettingoffairlywellfunctioningatrioventricularvalves.Downsyndromeis
presentinaboutthree-quartersofthesepatients,whichtosomecliniciansisa
furtherargumentagainstrepair.Suchpatientscanbeonlymildlysymptomatic.
