Andersons pediatric cardiology 963
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pointwhereweareoftenabletodeterminewhetheracompletesingle-stage
repairwithlowrightventricularpressurewillbepossiblebasedonpreoperative
anatomyandphysiology.Inparticular,virtuallyallpatientswithapreoperative
systemicoxygensaturationof85%orhigherwillhaveawell-developed
pulmonaryvascularbedandbeabletoundergosingle-stagecompleterepair.
However,inborderlinecases,wecontinuetoutilizetheintraoperativeflow
studytoassesstheeffectivetotalpulmonaryresistanceaftercompletionofthe
unifocalizationandpulmonaryarteryreconstruction.Theindicationsforan
intraoperativeflowstudyinourpracticenowincludepatientswitha
preoperativeoxygensaturationequaltoorgreaterthan82%orwhoareabove2
yearsofageatthetimeofunifocalization.Iftheflowstudydemonstratesahigh
pulmonaryarterypressure(>25to30mmHgdependingonage)during
graduallyincreasingpulmonarybloodflows(from20%to100%to120%ofa
normalcardiacoutput),acentralshuntisplacedfromtheaortatothe
unifocalizedpulmonaryarteries,aimingforameanpulmonaryarterypressureof
25to30mmHg,leavingtherightventricleuntouched.Closureusinga
fenestratedventricularseptaldefectpatchisnotperformed.Iftheflowstudy
demonstrateslowpulmonaryarterypressure(≤25mmHg)atphysiologiclevels
offlow,intracardiacrepairisperformed.Usingthesecriteria,werarelyhavea
fullyrepairedpatientwhoserightventricularsystolicpressureexceeds50%of
systemicsystolicpressure.Othergroupshavesubsequentlyreportedthevalueof
theintraoperativeflowstudy.33
Whencompleterepairisperformed,acardioplegianeedleisplacedinthe
ascendingaortaandtheaortaiscross-clamped.Cardioplegiaisadministeredto
achieveelectromechanicalsilence.Arightventriculotomyisperformedandthe
intracardiacanatomyinspected.Thepreviouslyharvestedautologous
pericardiumistrimmedtotheappropriatesizeforventricularseptaldefect
closureandsuturedinplace.Ifthereisaninteratrialcommunication,thisis
closedthrougharightatriotomy.Theaorticcross-clampisremoved.During
rewarming,therightventricle-to-pulmonaryarteryconduitissuturedinplace,
performingthedistalanastomosisfirst.Theproximalanastomosisisusually
augmentedwithananteriorpatchtomaintaintheproperorientationofthe
homograftvalve(Fig.36.19).Allsuturelinesareinspectedtoensurehemostasis.
Transthoracicpressure-monitoringlinesareplacedintheleftatriumandthrough
therightatriumintotherightventricle.Thepatientisweanedfrom
cardiopulmonarybypass,atransesophagealechocardiogramisperformedto
assessventricularfunctionandinspecttheintegrityoftherepair,andthevenous
cannulasareremoved.
FIG.36.19 Completeunifocalizationofmajoraortopulmonarycollateral
arteries(MAPCAs).(A)Completerepair,includingclosureoftheventricular
septaldefectandplacementofaconduitfromtherightventricletothe
reconstructedcentralpulmonaryartery.(B)Unifocalizationwithplacement
ofacentralshuntfromtheascendingaortatoreconstructedpulmonary
arterybed.(FromMainwaringRD,SheikhAY,PunnR,etal.Surgical
outcomesforpatientswithpulmonaryatresia/majoraortopulmonary
collateralsandAlagillesyndrome.EurJCardiothoracSurg.2012;42:235–
240.)
Whenapatientdoesnotpasstheintraoperativeflowstudyorifitwas
determinedinadvancetoperformunifocalizationwithoutcompleterepair,a
centralaortopulmonaryshuntisplacedtotheunifocalizedpulmonaryarteries.
Beforecomingoffbypass,aside-bitingclampisplacedonthecentralportionof
thereconstructedpulmonaryarteryandanexpandedpolytetrafluoroethylene
conduitisanastomosedend-to-sidetothepulmonaryarterywithrunningProlene
suture.Theclampisreleasedandhemostasisisensured.Thelengthoftheshunt
isestimatedanditiscutwithabeveltoalignwiththelateralaspectofthe
ascendingaorta.Aside-bitingclampisplacedonthelateralaspectofthe
ascendingaortaatthesamelevel,afterwhichtheexcludedportionoftheaortais
incisedandanastomosedtotheshuntinend-to-sidefashionwithrunning
Prolenesuture.Atemporaryhemoclipisleftinplaceuntilcardiopulmonary
bypassisweanedtoassesstheeffectoftheshuntonhemodynamics.Shunt
diameteristypicallybetween4and6mmdependingonthepatient'sweightand
theoverallcaliberofthepulmonaryvascularbed,withagoalmeanpulmonary
arterypressureof25to30mmHg.Ifnecessary,clipsareplacedontheshuntto
titratethepressuretothislevel.
CentralAortopulmonaryConnection(AortopulmonaryWindow).
Inpatientswithcompletedual-supplyMAPCAsandcentralpulmonaryarteries
thatarborizetoalloressentiallyalllungsegments,weperformanend-to-side
aortopulmonaryconnectionasthefirstproceduretofacilitategrowthofthe
pulmonaryarteries.ThetechniqueforthisprocedureisdepictedinFig.36.20
andwasdescribedpreviously.60Briefly,throughamediansternotomyand
limitedpericardialincision,thegreatarteriesaredissected.Themainpulmonary
arteryandcentralleftandrightpulmonaryarteriesaremobilized.Temporary
neurovascularclipsareplacedonthebranchpulmonaryarteries,andthe
proximalmainpulmonaryarteryisdividedascloseaspossibletoitsconnection
totherightventricle;theproximalendisoversewnorclippedifnecessary.The
mainpulmonaryarteryisexploredtodeterminethebestlocationforthe
anastomosis,takingcaretoavoiddistortionoftherightpulmonaryarterywhere
itpassesbehindtheascendingaorta.Inmostcasestheanastomosisistotheleft
posterolateralaspectoftheascendingaortajustabovethesinotubularjunction,
