Andersons pediatric cardiology 1286
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ArteryoftheFifthAorticArch
SaurabhK.Gupta,SimonD.Bamforth,RobertH.Anderson
Abstract
Mostembryologytextbooksshowsixpairsofpharyngealarcharteries,but
theexistenceofthefiftharcharteryhaslongbeencontroversial.Sixpairs
ofbilaterallysymmetricarteriesdevelopingwithinthepharyngealarches
haveyettobedemonstratedinanymammalianoravianspecies,but
collateralchannelsbetweenthedistalendsofthefourthandsixtharch
arteriesarefrequent.Wehavestudiedonlyonehumanembryoinwhichwe
foundachannelthatcouldpotentiallyqualifyasanarteryofthefiftharch.
Thepurportedchannelsnonethelessareinvokedwithincreasingfrequency
bypediatriccardiologiststoexplainvariouslesionsfoundincongenitally
malformedhearts,suchasdouble-barreledaortaandvarioussystemic-topulmonarychannelsfeedingthepulmonarycirculationinthesettingof
pulmonaryatresia.Abnormalbranchingofthebrachiocephalicarteriesis
alsofrequentlyinterpretedonthebasisofpersistenceoftheallegedartery
ofthefiftharch.Thischapterprovidesanaccountofnormaldevelopment
ofthearteriesformingwithinthepharyngealmesenchymeandextending
bilaterallytojointhedescendingaorta.Weshowthefeaturesofthesolitary
channelthatwebelieverepresentsthefiftharcharteryinahumanembryo.
Wethenprovideourowninterpretationofthevariousdescriptionswithin
theworldliterature,providingillustrationsofthosewebelievedeserve
recognitionasfiftharcharteries.Wesuggestthatmoreconvincing
alternativeexplanationscanbeadvancedtoaccountforthemajority.
Althoughtheinterpretationsdonotnecessarilychangetherapeutic
approachestothechannels,appropriatedescriptionisimportantintermsof
theirclassification.Thuswesuggestthat,ifitexists,afiftharchartery
shouldbeconfinedtotheextrapericardialspace,shouldarisefromthe
ascendingaortaproximaltotheoriginofbrachiocephalicarteries,andmust
terminateeitherinthedorsalaortaorintheconfluenceofpulmonary
arteriesviathepersistentlypatentarterialduct.
Keywords
embryology;arterialduct;pharyngealarcharteries;double-barreled
aorta;systemic-to-pulmonarycommunications;brachiocephalicarteries
