Andersons pediatric cardiology 1290
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FIG.48.6 Imagesshowingthecourseofthevesselfoundinasolitary
humanembryo,atCarnegiestage14,equivalenttoembryonicday10.5in
themouse,inwhichthereisevidenceofanarteryofthefifthpharyngeal
arch.(A)Obliqueviewofthechannelfromtheleftside,withthepharyngeal
endodermreconstructedingreen.(B)Leftlateralviewshowinghowthe
vesseliscontainedwithinadiscretesegmentofpharyngealmesenchyme.
Itjoinsthesixtharcharterytogainitsattachmenttothedorsalaorta.
CandidatesforPersistentFifthAortic
ArchArteries
Pediatriccardiologistshaveinterpretedmultiplechannelsfoundinthe
extrapericardialarterialpathwaysaspersistentarteriesofthefifthpharyngeal
pouch.13–73,78–106Followingasystematicreviewofthecasesexistingatthat
time,Freedomsuggestedthatthecandidatescouldbeclassifiedasproviding
systemic-to-systemicchannels,orsystemic-to-pulmonarypathways,pulmonaryto-systemicentities,ortheycouldpersistbilaterally.57Theinitialchannel
categorizedinthiswaywasasystemic-to-systemicchannelthatproduceda
double-barreledaorta.13Theauthorsoftheinitialdescriptionhighlightedthe
originoftheproposedfiftharchfromtheascendingaortaproximaltothe
brachiocephalicartery.Suchwastheimpactoftheirinitialobservation13that
manysubsequentinvestigatorslabeledanyvesselarisingfromthedistalpartof
theascendingaortaaspersistenceofthefiftharchartery.Wenowknowthat,
duringembryogenesis,thereisdifferentialgrowthofmedialandlateralsurfaces
oftheaorta.This,inturn,createsthepotentialformarkedvariationinthe
positionofthebrachiocephalicarteryrelativetothechannelpresumedtobethe
fiftharchartery.Thereisstillfurtherpotentialvariationintherelationshipofthe
proximaloriginofthearterialducttotheoriginofthebrachiocephalicartery.
Thisanatomicvariabilityfurthercomplicatestheassessmentofthethreedimensionalorientationoftheaorticarchanditsbranches,creatingparticular
difficultyindemonstratingclinicallythattheoriginofanyextravesselis
unequivocallyproximaltotheoriginofthebrachiocephalicartery.Althoughthis
maybepossiblewhenusingcomputedtomographyormagneticresonance
imaging,itisextremelydifficultifitisbasedsolelyonechocardiographic
interrogation,ashasbeenthecaseinmanyreports.41,45,47,65,69,102Itisalso
unfortunatethatallegedpersistenceofthearteryofthefiftharchhasbeencited
toexplainthemorphogenesisofseveralcongenitalmalformationswithoutany
attentiontothescantsupportthusfaravailablefromdevelopmentalstudies.108A
reassessmentofmany,ifnotmost,ofthesereports,includingthosedescribing
communicationswiththepulmonaryarteries,suggeststhattheymaybetterbe
consideredasrepresentingpersistingcollateralchannelsorelseexplainedonthe
basisofremodelingoftheaorticsacandthethird,fourth,andsixtharch
arteries.68,70,108
Double-BarreledAortaorDouble-LumenAortic
Arch
SubsequenttotheinitialinterpretationofferedbyVanPraaghandVanPraagh,13
whichwasendorsedenthusiasticallybyGerlisandcolleagues,21,23atleast44
casesofdouble-barreledaortahavebeenreportedasrepresentingfiftharch
arteries(Table48.1).Moreandmorecasesarenowlabeledinthisfashion
simplybecauseofthepresenceofthedouble-lumenaorta.However,manyofthe
investigatorsmakingthisdiagnosisfailtoassesstheoriginofthesecondchannel
relativetothatofthebrachiocephalicartery.Aswehaveemphasized,this
relationshipissubjecttoerrorifnotassessedcarefully.41,45,47,65,69,102Inoneof
ourowncaseswithdouble-barreledaorta,whichwestudied
echocardiographically,theoriginofarterialductproximaltothesecondchannel
suggeststhatthefindingsarebetterexplainedonthebasisofpersistenceof
collateralchannelscombinedwithremodelingofthelessercurvatureofthe
aorticarch(Fig.48.7).Itisdifficulttoaccountfortheproximallocationof
arterialductinthispatientifitispresumedthatthesecondchannelisa
persistentarteryofthefifthpharyngealarch.Thusfar,furthermore,mostclinical
investigatorsinterpretingdouble-barreledaortaonthebasisofpersistenceofthe
arteryofthefiftharchhavefailedtoconsiderthepossibilitythatthesecond
channelisnomorethanpersistenceofoneofthecollateralchannelsformed
betweenthedorsalinsertionsofthefourthandsixtharcharteries.Asalready
discussed,suchcollateralchannelswerefoundinuptohalfofourdeveloping
miceandarealsotobefoundindevelopinghumanembryos.3
Table48.1
AlltheCasesPublishedintheWorldLiteratureThatHave
ImplicatedPersistenceoftheArteryoftheFifthArchProducing
Double-BarreledAortaWithorWithoutPersistentPatencyofthe
ArterialDuctorCoarctationoftheAorta
1
2
3
Year
1969
1973
1973
Author
VanPraagh
Izukawa
Izukawa
Case
1
1
2
AnatomyoftheProposedFifthArch
Double-barreledaorta
Double-barreledaortawithpatentarterialduct
Double-barreledaortawithcoarctation
Reference
13
14
14
