Andersons pediatric cardiology 1761
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changesincollateralfloworQp:Qs,whichisquitevariableintheimmediate
postimplant,inflammatorymilieu.Anotheradvantageisifoxygenationbecomes
anissue;itissimpletotemporarilyaddanoxygenatortothecentrifugalsystem.
Althoughpatientscanbeextubatedandbesomewhatmobilewiththissupport
strategy,theEXCORsystemdoesallowformoremobilization,rehabilitation,
andtheabilitytobedischargedfromtheintensivecareunit,whichisveryrarely
donewithacentrifugalpump.Therefore,afterreachingastablestate(i.e.,
extubated,noinotropes,stableanticoagulation,andtoleratingenteralfeeds)and
understandingtheCOrequiredforthatparticularpatient,exchangingthe
centrifugalpumptotheEXCORpumpisareasonablepracticesothatthepatient
canbemaximallyrehabilitated.EXCORcannulaswithacentrifugalpumpis
becomingthestandardofcareforVADsupportofthosesmallerpatientswith
SVHs.
TheFontancirculationmayfailforavarietyofreasonsbutrarelydueto
isolatedsystemicsystolicventricularfailure,whichiswhytheMCSexperience
intheFontanhasbeeninconsistent.Whenconsideringmechanicalsupportofthe
Fontancirculation,onemustunderstandiftheissuesarerightsided,leftsided,
ormorelikelyacombinationofboth.Thuswithouttakinganinventoryofallthe
causesofwhyaparticularpatient'sFontancirculationisfailing,onecannot
understandthedominantcauseoffailureandthuswhethermechanicalsupport
orwhattypeofMCScouldbehelpful.Inaddition,aswithallothertypesof
heartfailure,therearedifferentstagesofFontancirculationfailureforwhich
differenttherapeuticsurgicalandmedicaltherapiesmayapply.
Fig.66.4demonstratesamultimodalityapproachthattakesintoaccountthe
stageandtypeofFontanfailureoccurring.Earlyfailure:ifanatrialFontanis
developingsymptomsand/orintraatrialreentranttachycardiaorifalateral
tunnelorextracardiacconduitFontanhasananatomicobstruction,Fontan
revisioncansuccessfullypalliatethesepatientsforquitesometime.63Late
failure:ifaFontanpatienthasprogressedtoarrhythmias(e.g.,atrialfibrillation)
recalcitranttotreatmentorbeginstoshowearlysignsofrenaland/orliver
dysfunction,oneshouldstartconsideringtransplantation64becausewaitinguntil
thereissignificantend-organdysfunctionwillsignificantlydecrease
posttransplantoutcomes.Inthecasewheresystemicventricularfailureisfeltto
bethemaincause,aVADcanimproveoverallcirculation.65However,onemust
knowtheend-diastolicsystemicventricularpressurepriortoVADimplantation
becauseifitislessthan12mmHg,thelikelihoodthatVADsupportwill
significantlyhelpislow.However,apressurelessthan12mmHgdoesnot
guaranteesuccessbecausepostimplantaninfectiouspulmonaryprocess,
transfusion-relatedlunginjury,oranysignificantpulmonaryprocesscan
significantlyaffectVADpreloadandright-sidedcongestion.EventhewellsupportedFontanpatientwithaVADisinadelicatebalance.Alowenddiastolicsystemicventricularpressureindicatesthattheright-sidedissuesare
likelythedominantcauseofthefailingcirculation.Ifvenouscongestionisto
blame,asubpulmonaryVADhasbeendescribedandhasonrareoccasions
successfullysupportedpatientstotransplant.66However,isolatedright-sided
supportisnotagoodlong-termVADstrategyforafailingFontancirculation
becauseforcingbloodthroughanabnormalpulmonaryvasculatureintowhatis
oftenarestrictivesystemicventriclewillnotbesustainable.IfaFontanpatient
awaitinghearttransplantdevelopsprogressivelyworseningend-organ
dysfunctionsecondarytosystemicventricularsystolicdysfunction,aVADmay
improvethepatient'soverallconditionandallowfordischargehomepriorto
transplant.Thefirstreportofapatientsuccessfullydischargedhomeaftera
failingFontansupportedbyimplantableVADwaspublishedin2011.65
ImplantationofaHeartMateIIalloweda15-year-oldboytoreturnhomeduring
72daysofsupportpriortotransplantandrepresentedahugestepinthecareof
thispatientcohortwithapplicationsfordestinationtherapyaswell(Table66.1).
Overall,66%ofthereportedFontanpatientsundergoingdeviceimplantation
havehadapositiveoutcome.
FIG.66.4 DecisiontreefortreatmentofthefailingFontanprocedure.Afib,
Atrialfibrillation;AP,atriopulmonary;EDP,end-diastolicpressure;IART,
intractableatrialreentranttachycardia;PLE,protein-losingenteropathy;
SVAD,singleventricleassistdevice;sx,symptoms;TAH,totalartificial
heart.
Table66.1
PatientsWithFontanPhysiologyUndergoingVADorTAH
Implantation,2008–2017a
Author
Prêtreetal.66
Riccietal.67
Russoetal.68
Age
Year N (Years),
Gender
2008 1 27,male
2008 1 15,male
2008 1 14,male
Cardarelliet 2009 1
al.69
Macklinget 2012 1
al.70
VanderPluym 2013 1
etal.71
VADType
Outcome
EXCOR(RVAD)
TandemHeart
CentrifugalVAD,
pneumatic
HeartMate
1.5,female EXCOR
Aliveondevice
Supportwithdrawnat10days,multiorganfailure
TransplantedwhileonHeartMate
4,female
EXCOR
Diedafter36daysofmultiorganfailure
2.8,male
CentriMag,
EXCOR,
CentriMag
Supportwithdrawnat54days,mesentericischemia
Recoveredandexplanted
