Andersons pediatric cardiology 952
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pulmonaryarteryfromtheascendingaorta(Fig.36.4).
FIG.36.3 Unifocalpulmonaryarterialsupplythroughconfluentpulmonary
arteriesfedbyapersistentlypatentarterialduct.Theaortahasbeen
turnedforwardandthebaseoftheheartisphotographedfromthefront.
FIG.36.4 Confluentpulmonaryarteriesarefedbyachannelarising
extrapericardiallyfromtheascendingaortajustdistaltothemarginsofthe
pericardialcavity.Thischannelislikelyapersistingarteryofthefifth
pharyngealarch.
MultifocalPulmonaryBloodSupply.
Thepresenceofamultifocalpulmonaryarterialsupplycreatestheclinical
complexityinTOF/PA.Themultiplevesselsfeedingthepulmonaryparenchyma
aresystemic-to-pulmonarycollateralarteries(Fig.36.5).
FIG.36.5 Systemic-to-pulmonarycollateralarteriesarisingfromthe
descendingaorta.(A)Thishearthasbeenreflectedtoshowtheoriginof
thearteriesfromtheposterioraspectofthedescendingaorta.(B)This
heartisshownfromthefront,demonstratingthepresenceof
intrapericardialpulmonaryarteries.Thevariationintheanastomoses
betweenthesystemic-to-pulmonarycollateralarteriesandthe
intrapericardialpulmonaryarteries,alongwiththeextentofthe
intrapericardialarteries,producesthecomplexityofthepulmonaryarterial
supply.
Confluentpulmonaryarteries.
Thecollateralarterieshardlyeverfeedalungthatalsoreceivessupplyviathe
arterialduct.Itisausefulworkingrule,therefore,toassumethatanarterialduct
willnotbepresentwhenalungissuppliedbysystemic-to-pulmonarycollateral
arteries.Althoughthesystemic-to-pulmonarycollateralarterieshardlyever
coexistinthesamelungwithanarterialduct,theydousuallycoexistwith
confluentintrapericardial(central)pulmonaryarteries(seeFig.36.5B).Insuch
circumstances,theconfluentpulmonaryarteriesareusuallyconnectedtosome
butnotallofthebronchopulmonarysegmentsofbothlungs.Instead,itis
typicallythecasethatdifferentarteriessupplydifferentsegmentsofthetwo
lungswithnointerconnectionsbetweenthem.Theconfluenceofintrapericardial
pulmonaryarteries,itselffedbyoneormoremajorsystemic-to-pulmonary
collateralarteries,isusuallyconnectedtothegreaterpartsofthelungs,butsome
componentsofthepulmonaryparenchymaaresupplieddirectlyandexclusively
bysystemic-to-pulmonarycollateralarteries.Theseindividualcollateralarteries,
therefore,canfeedindividualintrapulmonarysegments,orgroupsofsegments,
andarereferredtoasisolatedsupplycollaterals(Fig.36.6).Inaminorityof
cases,allofthecollateralsaredualsupply,meaningthattheyfeedapulmonary
arterytreethatarborizesfullytoallbronchopulmonarysegments.
FIG.36.6 Potentialcomplexityofthepulmonaryarterialsupplyina
hypotheticalpatientwithtetralogyandpulmonaryatresia.Thethree
segmentsoftherightupperlobeareshownwithexclusivesupplythrougha
systemic-to-pulmonarycollateralartery.Theremainderofthe
bronchopulmonarysegmentsarefedthroughintrapericardialpulmonary
arteriesbutwithanastomoseswithadditionalsystemic-to-pulmonary
collateralarteriesshownatthehilar,lobar,andsegmentallevels.
