Andersons pediatric cardiology 1903

Abstract
TheFontanoperationisthetreatmentofchoiceforpatientswitha
univentricularheart.Bydirectlyconnectingthesystemicveinstothe
pulmonarycirculation,itallowspartitioningofthecirculationsothat
systemicoxygensaturationandsingleventriclevolumearenormalized.The
Fontancirculationhassubstantiallyimprovedthelifeexpectancyinthis
groupofpatients.However,becausethereisnosubpulmonaryventricle,the
“Fontancirculation”comesatthecostofanelevatedcentralvenous
pressureandarestrictedcardiacoutput.Inadditiontolimitedfunctional
capacity,theFontancirculationhasaninsidiousimpactonmanyorgan
systems,includingtheliver,gastrointestinaltract,thehematologicand
immunesystems,andthekidneys.Morphologicfeaturessuchas
hypoplasticleftheartsyndromeareknowntoimpactoutcomeoverthefirst
andseconddecade.Aspatientssurviveintotheirthirdandfourthdecades,
theprogressionofmultisystemorgandysfunctionhasdeclareditselftobea
significantcontributortomorbidityandmortality.Thetreatmentof
problemssuchasprotein-losingenteropathyareevolving,asare
surveillanceprotocolsforotherabnormalitiessuchasFontan-relatedliver
orkidneydisease.Thetreatmentofthe“failingFontan”remainsa
challenge,particularlyinrelationtotheassessmentofsuitabilityfor,and
timingof,transplantation.Manyofthediseaseprocessessetinmotionby
theFontancirculationareuntreatableinisolation.Standardizedlifetime
surveillancemayplayaroleimprovingoutcomeandattentiontothe
psychologicalimpactofthisprocess,whichissimilartothatofother
chronicdiseases,isimportant.Thereareanumberofpromising
developmentsaimedatreducingcentralvenouspressureandimproving
cardiacoutputreserve,includingpulmonaryvasodilatortherapyand
exerciseprogramsthatmayalsoimprovesurvivalandqualityoflifeinthis
challengingpopulation.

Keywords

Fontan;univentricularheart;arrhythmia;mortality;riskfactors;heterotaxy


EvolutionoftheFontanProcedure
TheFontanoperationisthetreatmentofchoiceforpatientswithasingle
anatomicorfunctionalventricularchamber.Fromthelate1940s,survivorswith
afunctionallyuniventricularheartcouldbepalliatedwithasystemic-topulmonaryarteryorGlennshunt,butbytheearly1970s,only50%ofthosewith
tricuspidatresia—themostfavorableformoffunctionallyuniventricularheart—
survived15years(Fig.73.1).1Inthatera,complicationsofcyanoticheart
diseaseincludingstrokeandcerebralabscess,andprogressiveventricularfailure
andatrioventricularvalveregurgitationduetochronicvolumeloadingwerethe
commonestcausesofdeath.

FIG.73.1 Survivalcurveand95%confidenceintervalsof101patients
withtricuspidatresiabornafter1940andexaminedattheChildren's
HospitalMedicalCenter,Boston.(ModifiedfromDickM,FylerDC,Nadas
AS.Tricuspidatresia:clinicalcoursein101patients.AmJCardiol.
1975;36[3]:327–337,Fig.5.)

Theunderstandingthatbloodcouldflowthroughthelungswithouta
subpulmonaryventricleledtodevelopmentoftheFontanoperation,first
describedbyFontanandBaudetas“correctivesurgery”fortricuspidatresiain


1971.2Theoriginalprocedureconsistedofdivisionoftherightpulmonaryartery
fromthemainpulmonaryarteryandanastomosisofthesuperiorvenacavatothe
rightpulmonaryartery.Theleftpulmonaryarterywasthenanastomosedviaa
homograftvalvetotherightatrium,andthemainpulmonaryarterywas
disconnectedfromthehypoplasticventricle.Thevalvewasusedtopromotethe
“ventriculization”oftherightatriumsothatitmightgeneratesufficientpressure

toaugmentpulmonaryflow(Fig.73.2).Theatrialseptaldefectwasclosedanda
valveplacedatthejunctionoftheinferiorvenacavaandtherightatriumto
preventretrogradeflowduringatrialcontraction.Sixmonthslater,Dr.Guillermo
KreutzerandteamcarriedouttheirfirstatriopulmonaryFontananastomosis.
Thisprocedureincludeda6-mmfenestrationintheinteratrialseptumandas
suchwasthefirstfenestratedFontan.3Novalvewaspositionedinthevenous
circulationbecauseitwasthoughtthatthiswouldresultinadegreeof
obstruction—ahypothesisthatwasprovencorrectbecauseitsoonbecame
apparentthatvalveswithintheFontancirculationwereassociatedwithahigh
riskofstenosis.Thistechniqueevolvedtogenerateanatriopulmonary
anastomosisaswideaspossiblewithouttheuseofavalvedconduit(Fig.73.3).

FIG.73.2 Firstversionofthecorrectiveprocedureforthetreatmentof
tricuspidatresia,aspublishedbyFontanandBaudet.Therightpulmonary
arteryhasbeenanastomosedtothesuperiorvenacava,andtheleft
pulmonaryarterytotherightatrialappendage.Valveswereplaced
betweentheinferiorvenacavaandtherightatriumandbetweentheright
atriumandtheleftpulmonaryartery.(ModifiedfromFontanF,BaudetE.
Surgicalrepairoftricuspidatresia.Thorax.1971;26[3]:240–248.)