Andersons pediatric cardiology 1266
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(LAA;A)andarightaorticarch(RAA;B).Thetracheashowsslight
indentationonthesamesideoftheaorticarchandisbentslightlytothe
othersidewhenthereisanLAAorRAA.Theaorticarchcanbetraced
downwardtotheverticallinearstripeofthedescendingaortaonthesame
side(arrows).Inthesettingofadoubleaorticarch(C),thedistaltrachea
showsnarrowingonbothsides.Inthiscasethedescendingaortacanbe
traceddowntheleftside(arrows)andpneumonicconsolidationisseenin
therightmiddlelobe(C).
FIG.47.16 Lateralchestradiographs,correspondingtothoseshownin
Fig.47.15,show(A)anormalleftaorticarchandanormaltrachea,which
takesastraightcoursewithoutnarrowing.(B)Whentheaorticarchisright
sidedandanaberrantleftsubclavianarteryarisesfromadiverticulumof
Kommerell,thetracheaisbowedforwardbythediverticulum(arrows).(C)
Inthesettingofadoubleaorticarch,thedistaltracheainthiscaseshows
diffusenarrowing(arrow),andpneumonicconsolidationisseenintheright
middlelobe.
Althoughthebariumesophagographywaspreviouslyusedasavaluable
adjunct,itsuseisalmostabandonedcurrentlybecauseitdoesnotprovidea
definitivediagnosiswhileexposingthepatienttoradiation.6
Thedefinitivediagnosiscanbemadebyusingechocardiography,x-ray
angiography,computedtomography,ormagneticresonanceimaging.
Echocardiographyisalwaysindicatedwithaorticarchanomaliestoexcludeany
associatedintracardiacanomaly.Astandardizedechocardiographicapproachto
locatethepositionoftheaorticarchanditspatternofbranchingisalwaysan
essentialcomponentoftheevaluationofsuspectedcongenitalcardiacdisease.61
Forthispurpose,thetransducerispositionedtransverselyinthesuprasternal
notch,and,startingwithdownwardangulation,agentlesweepupwardallows
identificationoftheaorticarchpositionrelativetothetracheaandtheorigins
andbranchingpatternoftheheadandneckbranches(Fig.47.17).Inthenormal
leftaorticarch,thefirstbranchheadsrightwardandbifurcatesintotheright
commoncarotidandsubclavianarteries.However,intherightaorticarchwith
mirror-imagebranching,thefirstbranchheadsleftwardandbifurcatesintothe
leftcommoncarotidandsubclavianarteries.Ifthefirstbranchdoesnot
bifurcate,thenanaberrantsubclavianarteryshouldbesuspected(Fig.47.18).
Alternatively,acommonoriginoftherightbrachiocephalicandleftcarotid
arteries,oraseparateoriginoftheleftvertebralarteryproximaltotheleft
subclavianartery,canbothoccurinapproximately10%ofotherwisenormalleft
aorticarches.Inadoubleaorticarch,ifbotharepatent,bothcanbeidentifiedin
thistransversesuprasternalview.Echocardiographyhastheadvantagethatitcan
oftenbeperformedwithnoorminimalsedationatthebedside,andacomplete
diagnosiscanbereachedwithechocardiographyalonewhenthevascular
anatomyissimple,asinclassicformofdoubleaorticarch.8Oftenthe
informationprovidedbyechocardiographyisincomplete,andtheassessmentof
theanatomyoftheairwaysisnotpossiblewithultrasound.
FIG.47.17 Standardizedechocardiographicapproachtoshowthe
anatomyoftheaorticarchinapatientwithrightaorticarch(RAA)and
mirror-imagebranching.Thepositionoftheaorticarchrelativetothe
tracheaisidentifiedinadownwardtiltedtransverseviewfroma
suprasternalapproach(A).Sweepingupwardwiththetransducerpermits
ascertainmentoftheoriginsofthebrachiocephalicarteries(B).Thefirst
branchinthiscaseistheleftbrachiocephalicartery(LBA),whichbifurcates
intotheleftcommoncarotidartery(LCCA)andleftsubclavianartery(LSA).
Withafurthersweepupward,thecarotidandsubclavianarteriescanbe
imagedinanalmostsymmetricarrangementinthelowerneck(C).The
transducerisrotatedclockwiseorcounterclockwisetoaligntheascending
anddescendingaortawiththeaorticarch(D).Inthisinstance,the
sonographerhasmirror-imagedthetransducerclearlytodemonstratethat
thereisanRAA.LIA,Leftinnominateartery;LIV,leftinnominatevein;
RCCA,rightcommoncarotidartery;RPA,rightpulmonaryartery;RSA,
rightsubclavianartery;SCV,superiorcavalvein.
