Andersons pediatric cardiology 1345
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Introduction
Thevariousabnormalventriculoarterialconnections,suchastranspositioninits
regularorcongenitallycorrectedvariants,double-outletventricles,andcommon
arterialtrunk,areallcongenitalmalformationsinvolvingtheventricularoutflow
tract.Theyareoftendescribedintermsof“conotruncalmalformations,”butthis
termispoorlydefined.Ascurrentlyused,itrarelyincludeslesionsofthearterial
valves,whicharealsocomponentsoftheventricularoutflowtracts.Allthese
lesions,alongwithpulmonaryandaorticatresia,havebeendiscussedatlength
inthistext.However,severaladditionallesions,allofwhichinvolvedifferent
partsoftheoutflowtracts,arebestdescribedinaseparatechapter.Thereforethis
chapterdiscussesaortopulmonary(AP)windows,anomalousoriginofone
pulmonaryartery(PA)fromtheintrapericardialaorta,aortoventriculartunnels,
andaneurysmsoftheaorticsinusesofValsalva.Alsodiscussedistherare
situationofeitherduplicationofanoutflowtractortheevenmorerarevariantof
duplicationoftheaorticroot.Thischapterbeginswitharepriseofthenormal
anatomyoftheoutflowtracts.Itisaxiomaticthattheabnormalarrangements
cannotproperlybeappreciatedwithoutfullunderstandingofthenormal
situation.Untilrecently,itwasdifficulttoproviderationalexplanationsforthe
developmentofallthenormalcomponents,apartfromseekingtoexplainthe
morphogenesisofthemalformations.Theabilitytoillustratewithaccuracythe
temporaldevelopmentoftheoutflowtracts,asalreadydescribedinChapter3,
nowmakesitpossibletosuggestreasonswhytheoutflowtractsshoulddevelop
abnormallyinsuchawayastoproducethevariouslesions.Thereforethe
chapterincludesarecapitulationofthestepsinvolvedinnormalseparationof
theinitiallycommonoutflowtractintotheseparateoutletsfortherightandleft
ventricles,thearterialroots,andtheintrapericardialarterialtrunks.These
changesarerelatedtothepostnatalanatomyofthevariouslesionsasaprelude
todescribingtheirclinicalfeatures.
AnatomyoftheIntrapericardialOutflow
Tracts
Asdiscussedearlier,ithasbeenconventionaltodescribeboththedevelopment
andthemorphologyoftheoutflowtractsintermsofthetruncusandconus.This
approachhasprovenlessthansatisfactory,largelybecauseitignoresthearterial
roots,whichoccupyasignificantlengthwithinthemiddleofbothoutflowtracts
(Fig.51.1AandD).
FIG.51.1 Dissectionsofnormalheartsshowingfeaturesofthe
intrapericardialoutflowtracts.(A)Sectionpreparedtoreplicatetheoblique
subcostalechocardiographiccut.Itshowshowthepulmonaryoutflowtract
ismadeupoftheinfundibulum,thepulmonaryroot,andthepulmonary
trunk,thelatterbranchingatthemarginsofthepericardialcavity(arrows)
intotherightandleftpulmonaryarteries.Notethatthepulmonaryoutflow
tractisalmostatrightanglestotheaorticroot,whichiscutinshortaxis.
(B)Shortaxiscutacrosstheintrapericardialarterialtrunks,demonstrating
thateachpossessesitsowndiscretewalls.(C)Shortaxisoftheaorticroot
viewedfromabove.Thepulmonaryoutflowtracthasbeenreflected
forwardtoshowthespacebetweentheaorticandpulmonaryroots
(dashedline).Notetheextensivemuscularsubpulmonaryinfundibulum.
(D)Cutreplicatingtheparasternallong-axisechocardiographicprojection.
Itshowsthatthespacebetweentheroots(asshowninC)continues
proximallytoseparatethesubpulmonaryinfundibulumfromtheaorticroot.
Italsoshowsthethreecomponentsoftheaorticoutflowtract.Notethatthe
nonadjacentsinusoftheaorticrootisinfibrouscontinuitywiththeaortic
