Andersons pediatric cardiology 1169
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Abstract
Congenitalleftventricularoutflowtractobstructionaccountsfor10%ofall
congenitalheartdisease.Forpracticalpurposes,thesiteofobstructionis
classifiedanatomicallyasvalvar,subvalvar,supravalvar,oracombination
ofthethree(multilevelstenosis).Thedecision-makingprocessand
planningofinterventioniscomplicatedbytheheterogeneousmake-upof
patientswithleftventricularoutflowtractobstruction.Inneonates,the
criticalpointistodecidewhetherbiventricularrepairisfeasible.Patients
withisolatedstenosisandawell-developedleftventricleareoptimal
candidatesforbiventricularrepair.Attheotherendofthespectrum,theleft
ventricularoutflowtractobstructionmaybepartofacomplexcongenital
cardiacmalformationwithamorphologically,orfunctionally,borderline
leftventricle,withmultiplesequentialoutflowobstructions(Shone
syndrome,hypoplasticleftheartsyndrome,etc.)wheresingleventricle
pathwaymaybetheoptimalapproach.Growth,anactivelifestylewiththe
appropriateactivitylevel,andthedifficultiesinmedicalcompliance
representanotherspecificsetofrequirementsposedbythissubsetof
patients.Ingeneral,theprostheticmaterialsshouldnotcompromisecardiac
growthandlifestyle.Inparticular,reconstructionoftheaorticvalveand
pulmonaryautograftprocedureforreplacementoftheaorticvalveand
aorticroothasdramaticallychangedtheapproachtochildrenwith
congenitalaorticvalvediseaseandcomplexleftventricularoutflowtract
obstruction.Ontheotherhand,insomechildrenthebestalternativeisstill
touseamechanicalprostheticvalveorallograft,despitethewell-known
drawbacksoftheseprocedures.Innearlyallcases,congenitalleft
ventricularoutflowtractobstructionisalife-longcondition,whereby
interventionisonlypalliative,andthereisanongoingneedforfollow-up,
riskforcomplications,andpotentialneedforreintervention.
Keywords
Aorticstenosis;criticalaorticstenosis;aorticregurgitation;leftventricular
outflowtractobstruction;supravalvaraorticstenosis;subvalvaraortic
stenosis;aortic-leftventriculartunnel;openvalvotomy;balloondilatation
ofaorticvalve;reconstructionofaorticvalve;Rossprocedure;Ross-
Konnoprocedure;replacementofaorticvalve
Introduction
Itiswellrecognizedthatobstructionwithinoutflowtractofthemorphologically
leftventriclemaybeabovethearterialvalve,atthelevelofthevalveitself,orin
thesubvalvarregion.Thearterialvalveofthemorphologicallyleftventricle,of
course,althoughusuallyanaorticvalve,canbeapulmonaryvalvewhenthe
ventriculoarterialconnectionsarediscordant.Fromthemorphologicstance,the
samelesionsproducingsubaorticstenosisorregurgitationinthesettingof
concordantventriculoarterialconnectionswillproduceobstructiontoflowof
bloodtothelungswhentheconnectionsarediscordant.However,thespecific
anatomicdetailsofthelatterlesionsarediscussedinthechaptersdevotedtothe
variousclinicalformsoftransposition.Thereforethischapterisconcernedwith
thelesionsobstructingthemorphologicallyleftventricularoutflowtractinthe
settingofconcordantventriculoarterialconnections.
Suchcongenitalobstructionoftheleftventricularoutflowtractissaidto
accountfor5%ofallcardiacabnormalities.1Ifallthosepossessingaorticvalves
withtwoleafletswereincludedinthisnumber,themalformedaorticvalvemay
representthemostcommoncongenitalcardiacmalformation.2,3Itisdifficultto
determinethetrueincidencebecauseaorticvalveswithtwoleafletsmaynotbe
recognizedinchildhood.Consideredasagroup,75%ofthepatientswith
obstructiontooutflowfromtheleftventriclewillexhibitobstructionatvalvar
level.Apartfromthe1or2ineach100withsupravalvarobstruction,the
remainderwillhaveobstructivelesionsbelowthelevelofthevalve.Thethree
formsmayoccurseparatelyortogether,andeachmaybeassociatedwithaortic
regurgitation.Aorticregurgitation,irrespectiveofitscause,isdiscussedlaterin
thechapter.
