Andersons pediatric cardiology 1821

PhysiologicPrinciplestoMaximize
OutcomeinPatientsWitha
FunctionallyUniventricularHeart
GilWernovsky,JamesS.Tweddell


Abstract
Themanagementofneonates,infants,andchildrenbornwithafunctionally
univentricularheartisbasedonanumberofphysiologicprinciplesthat
havebeendevelopedandrefinedoverthepast3decades.Theoverarching
principleisaplannedseriesofsurgicalinterventionsculminatingina
Fontancirculationwithmaximaldurabilityandqualityoflife.Thiscentral
goalisachievedbycreatingacirculationthatprovidesthehighestpossible
cardiacoutputatthelowestpossiblecentralvenouspressure,bothatrest
andwithexercise.Theultimatesuccessofthisapproachdependsona
seriesofindividualproceduresperformed(1)attherighttimeand(2)with
technicalsuccess,followedby(3)appropriatemedicalmanagement,(4)
imagingsurveillanceand,whennecessary,(5)catheterinterventions.This
chapterdiscussesthephysiologicprinciplesthatunderpinthese
managementstrategiesaswellasthechangesthatoccurateachstageof
management.

Keywords
SingleVentricle;HypoplasticLeftHeartSyndrome;TricuspidAtresia;
BidirectionalGlenn;Fontan;PulmonaryOvercirculation


Introduction
Theadvancesmadeinthemanagementofnewbornsandinfantswithallforms
ofcriticalcongenitalheartdisease(cCHD)overthepast3decadeshavetruly
beenamongthetriumphsofcardiaccare.InallformsofcCHD,nearly

simultaneous,cumulative,andsynergisticadvancementshavebeenmadein
surgicalstrategies,anesthesiaandbypasstechniques,criticalcare,bedside
nursingcare,imaging,andcatherization;importantlyalso,anin-depth
understandingofthecomplexandvariablephysiologyseeninneonateswith
cCHDhasbeenachieved.Inparticular,theseadvanceshavegreatlyimproved
theoutcomeofbabiesbornwithafunctionallyuniventricularheart(fUVH).
Specifically,managementstrategies(e.g.,phosphodiesteraseinhibitors,nitric
oxide,flow-triggeredmechanicalventilation,noninvasivemonitoring,point-ofcaretesting)initiallystudiedinandappliedtoinfantswithabiventricular
circulationhavebeenextendedtothosewithafUVH,andtechniquesoriginally
specifictofUVHmanagementhavesubsequentlybeenappliedtoneonatesand
infantswithotherconditions(e.g.,archrepairfromamidlinesternotomy,hybrid
catheterization/surgicalstrategies,prolongedalphablockade,interstage
monitoring).1–11
Thischapterfocusesonmanagementprinciplesandpracticesforneonatesand
childrenwithafUVHwhoareundergoingstagedreconstruction,withemphasis
onthephysiologicconsequencesoftheunderlyingCHDandthechangesthat
occurinthetransitionalcirculation(seeChapter15),surgicalinterventions,and
patientgrowthalongtheFontanpathwaydepictedinChapter68.These
physiologicprinciplesaretheunderpinningsofsurgicalandperioperative
managementdiscussedinChapter71.