Andersons pediatric cardiology 1862
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shouldbepartofroutinepreoperativeevaluationofthechildwithfUVHpriorto
theFontanprocedure.Inparticular,thedevelopmentofvenovenouscollaterals
followingtheSCPCorpotentialvenovenouscollateralsaftertheFontanis
importantshouldtherebeunexplainedhypoxemiaaftersurgery.Also,many
patientsdevelopaortopulmonarycollateralsfollowingtheSCPC.Theprecise
etiologyoftheirpresenceandsizeisunknownbutspeculatedtoberelatedto
prolongedhypoxemia,inflammation,andsmallerpulmonaryarterysize.257–259
Thereisconsiderablecontroversyregardinginterventiononthesevesselsatthe
timeofpre-Fontanassessment.260,261Althoughaortopulmonarycollateralsmay
increasepulmonaryarterypressure,volumeloadtheventricle,andcomplicate
theconductofcardiopulmonarybypassandsurgery,alargeretrospectivereview
of539patientsconcludedthatthevariablepracticeofcoilingcollateralspreFontandidnotleadtoashorterlengthofstayorlateoutcomesfollowing
Fontan.21
Table71.9
ImportantElementsinthePre-FontanEvaluation
Hemodynamics
Systemicbloodflow
Pulmonarybloodflow
Pulmonaryarterypressure
Atrialpressure/end-diastolicpressure
Systemicandpulmonaryvascularresistance
Pressuregradients:cavoatrialjunction,atrialseptum,pulmonaryarteries,pulmonaryveins,
atrioventricularvalve,ventricularoutflowtract,aorticarch
Valvarregurgitantfraction
Anatomy
Superiorcavalvein
Inferiorcavalandhepaticveins
Pulmonaryarteries
Ventricularoutflowtract
Aorticarch
Other
Ventricularfunction
Atrioventricularvalveregurgitation
Venovenouscollaterals
Modality
Cath,CMR
Cath,CMR
Cath
Cath
Cath
Cath,CMR,
echo
CMR
Cath,CMR,
CT,echo
Cath,CMR,
CT,echo
Cath,CMR,
CT,echo
Cath,CMR,
CT,Echo
Cath,echo,
CMR
Cath,echo,
CMR
Cath,CMR,
CT
Aortopulmonarycollaterals
Cath,CMR,
CT
Cath,Cardiaccatheterization;CMR,cardiacmagneticresonance;CT,computedtomography;
echo,echocardiography.
Traditionallycardiaccatheterizationhasbeenusedtoevaluatethegreat
majorityoffactorsshowninTable71.9.CMRmaybeasafealternativeto
angiographyinanappropriatesubsetoflow-riskpreoperativeFontanpatients;
however,mostcentersstillroutinelyperformpreoperativecatheterization.262,263
Insummary,amultimodalapproachshouldbeutilizedandcustomizedtothe
individualpatient.264,265
SurgicalStrategies
1.ExtracardiacFontan
2.LateraltunnelFontan
3.ExtracardiacFontanwithcavoapicaljuxtaposition
4.Benefitsandrisksoffenestration
TheFontanisthelastplannedoperationintheFontanpathway(seealso
Chapter68)andisnearlyalwaysacompletionFontan,whichfollowsasuperior
cavopulmonaryconnection.ThecompletionFontanseparatessystemicand
pulmonaryvenousdrainageandrestoresin-seriescirculation,eliminating
hypoxemia.TheFontanpathwaycanbecompletedusingalateraltunnelor
extracardiacconduit.Inthecurrentera,thetimingofthecompletionFontanis
notcriticalandingeneraloccursat18monthsto4yearsofage.By2yearsof
age,thepulmonaryvasculatureisdevelopedsuchthatthecardiacoutputcanbe
accommodatedatamodestelevationofcentralvenouspressure.Thetypeof
completionFontanisdictatedbythekindofSCPCperformed.Ingeneral,a
lateraltunnelFontanischosenafterhemi-Fontanwhereasanextracardiac
FontanfollowsabidirectionalGlennshunt(Figs.71.11and71.12;Video
71.3).266,267
FIG.71.11 TheextracardiacFontanisconstructedusingatubegraftto
connecttheinferiorvenacavatothepulmonaryarteries.(FromKogonB.Is
theextracardiacconduitthepreferredFontanapproachforpatientswith
univentricularhearts?TheextracardiacconduitisthepreferredFontan
approachforpatientswithuniventricularhearts.Circulation.
2012;126:2511–2515.)
