Andersons pediatric cardiology 1058

Incidence
Commonarterialtrunkisarareanomaly.WithinthestateofTexas,the
prevalenceofnonsyndromiccommonarterialtrunkwas0.035per1000live
births,withasignificantincreaseintheriskoccurringwithadvancingmaternal
ageandmaternalresidenceneartheborderbetweenTexasandMexico.1
Extracardiacabnormalitiesarecommoninthesepatients.Of554patientswith
commonarterialtrunkenteredinthedatabaseoftheSocietyofThoracic
Surgeons,204hadsomeassociatednoncardiacabnormality,geneticabnormality,
orageneralizedsyndrome.2Theincidenceofcongenitalmalformationsofthe
heartisknowntobeincreasedintheoffspringofpatientswithcommonarterial
trunk,being6.6%intheoffspringofthosewithuncomplicatedlesionsand
13.6%ofthosewithcomplexformsofthecondition.3


Anatomy
Ofallthecongenitallesionsthatbenefitfrombeingdescribedina
straightforwardfashion,commonarterialtrunkisthemostobvious.When
describedintermsof“truncus,”whichisapoorlydefinedembryologicterm,it
isalwaysnecessarytoprovideasubsequentdefinitionofthelesionasseeninthe
postnatalheart.Describingtheentityasacommonarterialtrunknegatesthe
needforfurtherdefinition(Fig.40.1).Almostalways,thecommon
ventriculoarterialjunctionisguardedbyacommonarterialvalve.Rarecases
havenowbeendescribedinwhichthecommonvalveisdividedintoseparate
orificesfortherightandleftventricles,withtheraphebetweenthevalvar
orificesbounddowntothecrestoftheventricularseptumsothatshuntingtakes
placeatarteriallevel.4Thepatternofbranchingofthecommontrunkitselfcan
becomplicatedbyvariousarrangementsoftheindividualarterieswithinthe
systemic,pulmonary,andcoronaryarterialcirculations.Thepresenceofthe
commontrunk,nonetheless,distinguishestheentityfrompatientshavingdoubly
committedventricularseptaldefects,inwhich,althoughseparateaorticand
pulmonaryvalvarorificesarefoundwithinacommonventriculoarterial

junction,theshuntingisconfinedatventricularlevel.Italsodistinguishesthe
lesionsfromthe“closecousins”inwhichthereisawindowbetweenthe
intrapericardialcomponentsoftheaortaandpulmonarytrunk,andalsothose
patientsinwhichalargepatenttrunkleavesthebaseoftheheartincompany
withanatretictrunk,whichcanitselfbetracedfromitsoriginattheventricular
mass.However,onevariantthatcanstillgiveproblemsintermsofdescriptionis
whenthereiscompleteabsenceoftheintrapericardialpulmonaryarteries.
CollettandEdwards5includedthisvariantastheso-calledtypeIVwithintheir
overallgrouping.However,thetrunkarisingfromtheventricularmassinthis
settingisbestdescribedasasolitary,ratherthanacommon,trunk.Thisis
becausethereisnowayofknowing,hadtheybeenpresent,whetherthe
intrapericardialpulmonaryarterieswouldhaveoriginatedfromthearterialtrunk
orfromtherightventricularoutflowtract(Fig.40.2).Intermsofclinical
presentationandtreatment,suchpatientswithasolitaryarterialtrunkhavemore
affinitieswithtetralogyandpulmonaryatresia(seeChapter36)thanwith
commonarterialtrunk.


FIG.40.1 Commonarterialtrunkexitingfromtheventricularmassthrough
acommonventriculoarterialjunctionguardedbyacommonarterialvalve
andsupplyingdirectlythecoronary,systemic,andpulmonarycirculations.

FIG.40.2 Hadthepulmonaryarteriesbeenpresentinthehearts
illustrated,theycouldhaveariseneitherfromtheheart(A)orfromthe
arterialtrunkitself(B).Thereforethereisnowayofknowingwhetherthe
trunkitselfwasdestinedtobecomeanaortaoracommontrunk.Because
ofthisuncertainty,itisbestdescribedasasolitarytrunk.However,patients
withthisarrangementarebestconsideredasasubsetofthosewith
tetralogyandpulmonaryatresia.