Andersons pediatric cardiology 962
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FIG.36.17 Surgicalexposureusedtoaccessthemajoraortopulmonary
collateralarteries(MAPCAs)fromthedescendingaorta(D.Ao).Theaorta
(Ao)andthesuperiorvenacava(SVC)areretractedlaterallytoopena
windowcraniadtotheleftatrium(LA),whichallowsthetransversesinus
andsubcarinalspacetobeopenedandtheairwayanddescendingaortato
beidentifiedandaccessed.Ac,Aorticcannula;IC,inferiorvenouscannula;
LV,leftventricle;RA,rightatrium;RV,rightventricle;SC,superiorvenous
cannula.(FromReddyVM,LiddicoatJR,HanleyFL.Midlineone-stage
completeunifocalizationandrepairofpulmonaryatresiawithventricular
septaldefectandmajoraortopulmonarycollaterals.JThoracCardiovasc
Surg.1995;109:832–845.)
Weattempttoremainoffbypassforthedissectionandmobilizationof
MAPCAsandevenforinitialpartsoftheunifocalizationreconstruction.
However,eventuallyprogressivecyanosisand/ortheneedtodecompressthe
heartandlungsfortechnicalreasonsrequirestheinstitutionofcardiopulmonary
bypass.Purse-stringsuturesareplacedintheascendingaorta,superiorvena
cava,inferiorvenacava,andrightsuperiorpulmonaryvein.Heparinis
administeredandthevesselsarecannulated.Oncebypassisinstituted,the
MAPCAsareimmediatelyclippedattheaorticoriginstofacilitatecontrolled
perfusion.Thepatientiscooledto25°Ctoreducethemetabolicrateandpump
flowismaintainedat100mL/kgperminute,whichreducestheamountof
collateralflowduringthereconstruction.Duringbypass,thearterialPCO2is
maintainedatabove45mmHgtomaximizecerebralbloodflow.
Theunifocalizationisperformedwithoutclampingtheaortatomaintain
perfusiontothedecompressedbeatingventricles,andtheprocessis
individualizedbasedontheanatomyofthepulmonaryarteriesandMAPCAs.
Thedistalbranchesareprobedwithmetalsizerstoassessdiameter,orientation,
andthepresenceofstenoses.Inanefforttominimizerecurrentstenosis,we
attempttoutilizeasmuchnativetissueaspossibleforanastomosesand
pulmonaryarterialreconstruction.Extensivedistaldissectionandmobilization
intothesegmentallevelbranchesofallavailableMAPCAsmaximizesvessel
length,facilitatingatension-freereconstruction.Wheneverpatchaugmentation
ofnewlyunifocalizedbranchvesselsisrequired,fullycircumferentialpatchesor
conduitsareavoidedinordertopreservethegrowthpotentialofnativetissue.
Patchaugmentationisperformedexclusivelywithcryopreservedpulmonary
arterialhomograft,whichwehavefoundtoprovidedurablelong-termresultsfor
thesereconstructionsinchildren.AnastomosesbetweenMAPCAsorof
MAPCAstopulmonaryarteriesareperformedwithextendedside-to-side
connectionsratherthanend-to-sideconnectionswheneverpossible,usuallywith
connectiontotheposteriororsuperior/inferior-posterioraspectofthecentral
pulmonaryartery(Fig.36.18).Theseanastomosestypicallyextendintothelung
parenchyma,wherethecollateralvesselsalmostalwaystakeonthephysical
characteristicsofnativepulmonaryarteries.MostoftheMAPCAscanbe
unifocalizeddirectlytothecentralpulmonaryarterysystemwithinthedissected
mediastinalspace.Mostanastomosesareperformedinthedissectedcentral
mediastinum;rarelyifeverarecollateralsroutedoverthehilarstructures.
Stenoticbranchesareopenedlongitudinallyandaugmentedwithapatchof
pulmonaryarteryhomograft.Allanastomosesandpatchaugmentationsare
performedusing8-0Prolenesuture.Ifthecentralpulmonaryarteryrequires
additionalaugmentation,itisincisedandpatchedwithpulmonaryhomograft
anteriorlytoalarger-than-normaldiameter.Ananimatedinteractive
unifocalizationsimulationcanbeexperiencedat
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FIG.36.18 (A)Nativeanatomyofcentralpulmonaryarteriesandthree
majoraortopulmonarycollateralarteries(MAPCAs)inayounginfant.(B)
DissectedandmobilizedMAPCAsandpulmonaryartery.(C)
UnifocalizationoftheMAPCAsandpulmonaryarteries.Dashedlinesin(B)
representincisionsinthevessels.Correspondingcontiguousletters(e.g.,
A–A′andB–B′)indicatepointsatwhichtheMAPCAsandpulmonary
arteriesareconnected.Thisreconstructionwouldbecompletedby
augmentingtheanteriorunifocalizedpulmonaryarteriesandplacingaright
ventricletopulmonaryarteryconduit.AO,Aorta;LPA,leftpulmonaryartery;
RPA,rightpulmonaryartery.(FromReddyVM,LiddicoatJR,HanleyFL.
Midlineone-stagecompleteunifocalizationandrepairofpulmonaryatresia
withventricularseptaldefectandmajoraortopulmonarycollaterals.J
ThoracCardiovascSurg.1995;109:832–845.)
Inourexperience,themajorityofpatientsundergoingmidlineunifocalization
areabletohaveasingle-stagecompleterepairwithclosureoftheventricular
septaldefectandplacementofaconduitfromtherightventricletothe
reconstructedpulmonaryarteries.Earlierinourexperience,wedevelopedan
intraoperativeflowstudytoallowestimationoftotalpulmonaryresistanceafter
unifocalizationandallowdata-drivendecision-makingaboutclosingthe
ventricularseptaldefect.38Inourcurrentpractice,however,wehavereacheda
