Andersons pediatric cardiology 2258
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CongenitalHeartDefect
Transpositionwithintact
ventricularseptum
Transpositionwith
ventricularseptaldefect
Obstructedtotal
anomalouspulmonary
venousreturn
Ductdependentsystemic
circulation
Ductdependent
pulmonarycirculation
SpecificConsequencesofLatePresentation
Regressionofleftventricularmassthatmayprecludeasuccessfularterialswitchor
increaseriskofmortalityandmorbidity;Hypoxicinjurytobrainandotherend-organs
Developmentofpulmonaryvascularobstructivedisease;Undesirabledilationofthe
neoaorticroot,refractorypneumonia
Delayedpostoperativerecoveryfrompulmonarycongestion,pulmonaryhypertensive
crisisinthepostoperativeperiod,ventriculardysfunction
Widespreadorgandysfunctionfromhypoperfusion:Renalfailure,seizures,liver
dysfunction,necrotizingenterocolitis,andbloodstreamsepsis
Prolongedhypoxemiawithattendantconsequencesasabove
Thelatepresentinginfantwithtranspositionofgreatarteriesisuniqueto
LMICs,andthemanagementoftheregressedleftventricleinthissituationhas
beenthefocusofmuchdebate.Theoptionsvaryfromattemptsatretrainingthe
leftventriclepriortoanarterialswitch30tosupportingtheleftventriclewith
mechanicalsupportafteradelayedprimaryarterialswitch.31Eitheroption
involvessignificantresourceutilizationandtheneedforgreatexpertisein
perioperativemanagementforoptimaloutcomes.Giventhepaucityof
availabilityofbothresourcesandexpertiseinmostplaces,theatrialswitch
operation(Senningprocedure),whichmaybeeasiertoperformandhasmore
predictableearlyoutcomes,isalsoanoptionforthelate-presentingtransposition
withintactventricularseptuminLMICs.
PulmonaryHypertensioninShuntLesions.
Inadvancednations,thewidespreadavailabilityofheartsurgeryintheinfanthas
largelyeliminatedtheproblemofchildrenwithleft-to-rightshuntspresenting
latewithpulmonaryhypertension.Typically,theselesionsare“posttricuspid”
shunts(theselesionsarelargeVSDsandPDAs).However,inLMICsthevast
majorityofinfantswithlargeshuntsareleftunoperatedbecauseoflimitationsin
accesstoinfantheartsurgery.Thereisalsoaprevailingmisconceptionamong
manypediatriciansthatmostseptaldefectsarelikelytoclosewithtime.This
resultsinprematuredeathamongmanyinfantswhooftensuccumbtoheart
failureandrefractorypneumonia.Amongsurvivors,awideclinicalspectrumof
possibilitiescanbeseenthatislargelydeterminedbythedegreeofelevationin
pulmonaryvascularresistance(PVR).Atoneendofthespectrumarechildren
whoarefortunateenoughtoremainoperablewithminimalelevationsinPVR.32
AttheotherendarepatientswithfrankEisenmengersyndromewithshunt
reversalandhypoxemiaresultingfromsevereirreversibleelevationinPVR(Fig.
88.1).Includedinthisspectrumarepatientswhoareoftenlabeledas
“borderline.”Theypresentanimportantchallengeindecision-makingregarding
operability.Theavailableguidelinesarelargelybasedonexpertconsensusthat
isnotyetsubstantiatedbyevidencefromappropriatelydesignedprospective
studies.33TherearenoclearlydefinedthresholdsforPVR,ratiosofpulmonary
andsystemicvascularresistance,andresponsetoselectivepulmonary
vasodilatorsthatconsistentlyseparatethe“operable”from“inoperable.”Thisis
becausethereareinherentlimitationsinaccuracyofdataobtainedthrough
cardiaccatheterization.
FIG.88.1 Profileofa26-year-oldwithalargeventricularseptaldefect
whowasseenininfancyforsymptomsoffailuretothriveandfrequent
respiratoryinfections.Hewasaskedtowaituntilheweighed10kgto
permit“safesurgery.”Notethedilatedcentralpulmonaryarterieswith
reducedperipherallungvasculature(A)andclubbingandduskinessof
fingernails(B).Theelectrocardiogram(C)showsdominantrightventricular
forcesandrightaxisdeviation.
Aholisticapproachthatintegratesclinical,noninvasive,andinvasivedatais
oftenusedtomakeadecisioninthischallenginggroupofpatients.32Surgical
strategiesinsuchpatientshaveinvolvedtheuseoffenestratedorvalvedpatches
toclosetheatrialorventriculardefectsthatwouldallowdecompressionofthe
rightheartintheeventofapostoperativepulmonaryhypertensivecrises.34,35
Selectivepulmonaryvasodilators,typicallyendothelinreceptorantagonists
(bosentanorambrisentan)andphosphodiesteraseinhibitors(sildenafiland
tadalafil),areusedforvariableperiodsbeforeandaftersurgeryinthese
situations.36,37However,thereisnoconclusiveproofwhetherthestrategyof
“repairandtreatortreatandrepair”resultsinasustainedfallinPVR.An
additionalconsiderationisthealtitudeoftheirresidence.Aborderlinecaseatsea
levelmaynotbeoperableiftheyreturnhometo4000m.
Childrenwithcyanoticheartdiseaseandincreasedpulmonarybloodflow
(suchaspersistenttruncusarteriosusortranspositionwithalargeVSDorlarge
patentarterialduct)haverapidandmorepredictableonsetofelevationinPVR
andtendtobecomeinoperableatarelativelyearlyage.32Childrenwitha
functionallyuniventricularheartalongwithincreasedpulmonarybloodflow
oftenmisstheiropportunitytogetaFontanoperationbecausetheinitial
palliation(typicallyapulmonaryarterialband)isdelayedconsiderably.Delays
insurgeryforcomplexCHDareparticularlycommonbecausetheseoperations
areexpensiveandfewcentershavethecapabilitytodealwiththem.
ConsequencesofLong-StandingandSevereHypoxemia
Neurologicandneurodevelopmentalconsequences.
ChildrenwithCHDandthepotentialforright-to-leftshuntingexperiencea
varietyofadverseconsequencesthatresultfromlong-standinghypoxemia.
Overtneurologiccomplicationsarecommonintheformofstrokesdueto
paradoxicalembolusorseverepolycythemia.38Severeneurologicinsultcan
resultfromtransientintensehypoxemiasuchasduringacyanotic“spell”(Fig.
88.2).Irondeficiencyanemiapredisposestooccurrenceofcerebralinfarctions
presumablybyalteringtherheologyofredbloodcells.38Thesecellsaggregate
andclogthemicrocirculationofthebrain.
