Andersons pediatric cardiology 1924

Fontanriskprofileinthatgroupwasnodifferenttothatofthosewhowith
fenestrationclosure.Thesefindingssuggestthatastrategyofselectiveclosure
canbeusedtoidentifyahigh-riskpopulation,whodespitetheirpooreroutcome
maywellhaveabetteroutcomewithapersistentlypatentfenestrationthanwith
theirfenestrationclosed.

FIG.73.24 Freedomfromdeathbetweenopenandclosedfenestration
(A)andstratifiedbymechanismoffenestrationclosure(B).Thepresence
ofanopenfenestrationwasassociatedwiththelowestsurvival.(From
KotaniY.,ChetanD,SaediA,etal.Persistentfenestrationmaybea
markerforphysiologicintoleranceafterFontancompletion.JThorac
CardiovascSurg.2014;148:2532–2538,Fig.1.)

Informationcomparingexerciseperformancebeforeandafterfenestration
closureissparse.Inonesmallstudytherewasanimprovementinventilatory
efficiencyasmeasuredbyadecreaseinVEandanincreaseintheVE/VCO2
slope,withoutachangeinexercisecapacity,351whereasinanother,exercise
durationandmaximalexercisecapacityincreased.352Despitethetheoreticalrisk
ofthromboembolismduetotheobligatoryright-to-leftshuntandapropensity
forvenousthrombosis,anumberofstudieshavebeenunabletodemonstratean
associationofthiscomplicationwithapersistentfenestration.292
Giventheaforementioned,thereisconsiderablepracticevariabilityinrelation
tofenestrationclosureanditstiming.249Earlyinthecourseofpractice,closure
wasundertakenshortlyafterrecoveryfromtheFontanoperation.Therealization
thatasignificantminorityoffenestrationsclosespontaneouslyaftertheFontan
operationledtoadelayinclosure.353Thetimecourseofspontaneousclosureis
notwellunderstood.Somerecommendclosure12monthsaftersurgeryand


othersupto3yearslater.Whenclosureisconsidered,testocclusionwitha
ballooncatheterwithside-holesproximaltotheballoon(e.g.,Berman

angiographic)isrecommended(Fig.73.25)(Videos73.5and73.6).Oxygen
saturationandpressureshouldbemeasuredsimultaneouslyintheFontan
pathwayandthesystemicarterialcirculations.Criteriatopredict“failure”oftest
occlusionarepoorlydefined,butiftestocclusionisassociatedwithaFontan
pathwaypressuregreaterthan18mmHg,afallintheFontanpathwayoxygen
saturationorafallinthesystemicbloodpressurethenclosureisnotadvised.353
Likewiseifthesystemicoxygensaturationdoesnotincreaseabove90%,
fenestrationclosuremaynotimprovesystemicoxygensaturationandanother
sourceofright-to-leftflowsuchasasystemicvenoustoatrialshuntor
pulmonaryarteriovenousmalformations,oralternatelylungdisease,shouldbe
considered.Withtheseprecautions,theriskofdecompensationandFontan
failurerelatedtofenestrationclosureislow.353

FIG.73.25 Angiogramsinapatientwithafenestratedextracardiac
Fontandemonstrating(A)patentfenestration(asterisk),(B)testocclusion
ofthefenestration(arrowmarksocclusionballoon),and(C)device
occlusionofthefenestration(arrowmarksdevice).

VenovenousCollaterals
Venovenouscollateralsareacommoncauseofprogressivecyanosisafterthe
Fontanprocedure.Thesevesselsconnectthesystemicvenouscirculation(most
oftenfromtheupperthorax)tothepulmonaryveinsordirectlytothesystemic
venousatrium.Manywereoriginallysmallveins.Dilatationoccursbecauseof
increasedflowdrivenbythepressuregradientbetweenthesystemicand
pulmonaryveins.Thistranspulmonarypressuregradientincreasesifthereis


pathwayobstructionatanylevel,includingstenosiswithinanextracardiac
conduit,atthecavopulmonaryanastomosis,withinthepulmonaryarteries,
pulmonaryvasculardiseaseorotherlungdiseaseresultinginelevated

pulmonaryvascularresistance,orpulmonaryveinstenosis.Largercollateralsare
associatedwithalongertimesincetheFontanprocedureandahigherpulmonary
arterypressure(Fig.73.26).354Transcatheterocclusionofvenovenocollaterals
willresultinanincreaseinsystemicarterialoxygensaturation.However,
venovenocollateralsareoftenamarkerofproblemswithintheFontan
circulation.Byallowingaportionofsystemicvenousreturntobypassthe
pulmonarycirculation,theyfulfilltheroleofafenestration,maintainingcardiac
outputandreducingCVP.Arecentreportdemonstratesanincreasedmortality
riskintheyearsaftervenovenouscollateralclosure,with50%ofdeaths
occurringinpatientswithapulmonaryarterypressuregreaterthan18mmHg
(Fig.73.27).355Thesefindingsindicatethat,insomepatients,venovenous
collateralsmaybeadvantageousforlong-termsurvival.Asearchforpotential
riskfactorsandtestocclusioninasimilarwaytothatrecommendedpriorto
fenestrationshouldbeconsideredpriortoocclusion.

FIG.73.26 (A)Venovenouscollateral,originatingfromthe
brachiocephalicveinanddrainingtoaleftpulmonaryvein.(B)Following
coilocclusion.