Andersons pediatric cardiology 329

carefulclinicalassessment.Clinicalsignsofcirculatorycompromiseinclude
tachycardia,hypotension,anddecreasedurinaryoutput.Plasmalactate,arterial
pH,basedeficit,andmixedvenousoxygensaturationsshouldbemonitoredas
markersoftheefficacyoftissueoxygenation.ArterialPaCO2andpHshouldbe
carefullycontrolledtoavoidexcessivepulmonaryvasodilationthatinthecaseof
shuntinglesionscancompromisesystemicperfusion.Especiallywithcyanotic
lesions,orthosepronetoright-to-leftshunting,thereisariskofinadequate
systemicoxygendelivery.Theabilitytoregulatecerebralbloodflowis
importantinpreventingsecondaryischemicandhemorrhagicdamageinthe
developingbrain.Therelationshipbetweenarterialbloodpressureandregional
cerebraloxygenationasanestimateofcerebralbloodflowcanbeapproximated
bynear-infraredspectroscopy.298Followingitsrapidadaptationintotheclinical
area,rigorousstudiesnowsupportitsuseinselectcircumstances.299Regardless,
likealltechnologies,acriticalevaluationofdatageneratedmayhelptorefine
areaswhereitismostuseful.300,301

CardiovascularSupport
Thegoaloftreatmentistoensurethatsystemicperfusionismaintainedwithina
rangetosustainadequatetissueoxygenation.Therapeuticoptionsinclude
volumeexpansion,inodilatordrugssuchasdobutamineandmilrinone,or
pressorssuchasdopamine,epinephrine,andvasopressin,ashavebeendiscussed
previously.Volumeexpansionisusefulinneonateswithabnormalright
ventricularperformance;henceitmayplayanimportantroleinthecareof
neonateswithelevatedpulmonarypressuresorduct-dependentpulmonary
circulationssuchasthosewithpulmonaryatresiaorseveretetralogyofFallot.302
Milrinonehasbeenshowntoreducebothmortalityandlowcardiacoutput
syndromeinpostoperativecardiacpatientsand,formanysystems,playsakey
roleonmanagementofthesepatients.212,303Equallyimportantasthespecificsof
therapeuticchoicesisaconsistentmanagementstylewithinthecenterthatcares
forthepatient.

Interventional
Cardiaccatheterizationisoccasionallyperformedintheprematureneonate.
Successfulballoondilationofthepulmonaryvalveinneonateshasproduced
goodlong-termresults,althoughlowerbodysurfacearearemainsariskfactor


forpulmonaryinsufficiency.304,305Anothercommonprocedureisbedside
balloonatrialseptostomyinneonateswithtranspositionofthegreat
arteries.306,307Controversyhassurroundedtheincreasedincidenceofstroke
followingballoonatrialseptostomy,withdifferentinstitutionsreporting
conflictingresults.308,309However,newdatasuggestthatadditionalfactorsmay
playaprimaryroleonneurologicinjuryinpatientsundergoingthisintervention,
includingtheongoingriskofparadoxicalembolusfromroutineaccessprovided
intheintensivecareunitintheuncorrectedcirculation.310,311Indeed,prenatal
echocardiographymayhelptopredictthosepatientswhorequireseptostomy,
thusreducingthenumberofemergentproceduresandreducingrisk.312A
particularlychallenginggroupofpatientsarethesubgroupofpatientswith
hypoplasticleftheartsyndromewitharestrictiveatrialseptumthatrequire
urgentseptostomy.276Fetalinventionsforthisandothercongenitalheartlesions
suchasotherformsofmitralatresiaandcriticalaorticstenosiscontinueto
improveandmayimpactthecareofprematureinfantswithcomplexheart
disease.313,314

SurgicalProcedures
Decisionsrelatedtotheoptimaltimingforsurgeryarechallengingduetothe
combinedeffectsofimmaturity,lowbirthweight,andassociated
comorbidities.181,182,186,187,315,316Traditionally,anexpectantapproachhasbeen
preferred.However,delayingsurgeryuntilimmatureneonatesreacha
predeterminedmaturityandweightmayincreasetherisksofpreoperative,
perioperative,andpostoperativemorbidity(seeFig.15.14).317,318Thisis

particularlythecaseforneonateswithestablishedchroniclungdisease.Inmany
centers,althoughtheaverageweightatsurgeryisgreaterthan2000g,surgical
interventioniscommonlyattemptedatlowerweights.186,319Forexample,
ligationoftheductusarteriosusiscommoninprematureneonates.Asa
relativelystraightforwardbedsideprocedure,itistemptingtounderplaythe
perioperativeconsequences.Althoughtheductcanbeclosedroutinelywithout
mortality,theprocedurecanresultinprofoundperioperativeswingsandthus
needstobeconsideredcarefully.320Valvarreplacementisrarelyperformedin
prematureneonates,althoughballoonvalvuloplastyforcriticalaorticand
pulmonarystenosisiscommon.Therehasbeenarecentreevaluationofthe
relativeshort-andlong-termmeritsofaninterventionalcatheterizationapproach


versusaprimarysurgicalapproachofopenvalvotomy.Withproponentsonboth
sides,itisprematuretodefinitivelydeclareabestapproach.321–324Likely,more
refineddiagnosticswillenableriskstratificationofpatientstoeither
catheterizationorsurgery.Theserisksareamplifiedinconditionssuchas
hypoplasticleftheartsyndromethatrequireneonatalpalliation.325Aparticular
focushasbeenontheneurologicconsequencesofsurgeryonpreterminfant,and
atlessthan39weeks’gestation,outcomesdecline.326,327Thesedatachallenge
thepracticeofelectivepretermdeliveryoffetuseswithcomplexCHD,
emphasizingtheimportanceofateamapproachthatincludesmaternalfetal
medicine,obstetrics,neonatology,pediatriccardiology,surgery,anesthesia,
nursing,andcriticalcare.Innoncardiacsurgeryforpatientswithcardiacdisease,
caremustbetakentoensurethestabilityofthephysiologyoftheunderlying
cardiaclesion.328Theuseofadedicatedcardiacanestheticteamtoperformall
procedures,cardiacandnoncardiac,onpatientswithcardiacdiseaseisbecoming
anincreasinglyacceptedapproachtomaximizeresults.