Andersons pediatric cardiology 1085

communicationislargeanddoesnotcauseacontinuousmurmur.Evenwith
carefulaortography,thisconditionmaybemisdiagnosed.Echocardiography
shouldnowhelptoavoidthiserror.Majoraortopulmonarycollateralarteries,
pulmonaryarteriovenousfistulas,andcollateralarteriesassociatedwith
coarctation,allcausecontinuousmurmurs.Theseseldomcausediagnostic
problemsbecauseofthegeneralclinicalpictureandthelocationofthemurmur.
Othercausesofcontinuousmurmursheardinthechestincluderupturedsinusof
Valsalva,peripheralpulmonaryarterialstenosis,commonarterialtrunk,
coronaryarteryfistulas,thesupracardiacformoftotallyanomalouspulmonary
venousconnection,mitralatresia,surgicallycreatedsystemic-to-pulmonary
arterialshunts,andrarelyanomalousoriginoftheleftcoronaryarteryfromthe
pulmonarytrunk.Prolapseofanaorticvalvarleafletintoaventricularseptal
defectmayalsosimulatepersistentpatencyoftheduct.Most,ifnotall,ofthese
potentialpitfallscanbeavoidedbycarefulclinicalevaluationandgood
echocardiography.

NaturalHistory
Likemostcongenitalcardiacmalformations,reliableinformationaboutthe
naturalhistoryofuntreatedpatientswithapersistentlypatentductisnonexistent.
Availabledatastemfromtheshortperiodoftimethatelapsesbetweenthe
conditionbeingdiagnosedwithanyfrequencyandtoitsbeingrelievedbyan
operation.Campbell75attemptedanoverviewofthenaturalhistory,basedonhis
ownextensiveclinicalexperienceandontheliterature.Inevitably,such
calculationstendtooveremphasizethenumberofpatientswhoexperience
events,betheyfavorableoradverseandunderestimatethenumberofpatients
withanasymptomaticandundetectedduct.

SpontaneousClosure
Bydefinition,apersistentductisonethatremainsopenbeyond3monthsinan
infantbornatfullterm.Delayedclosureinprematureinfants,orthatoccurring
withinthefirst3months,isthereforeexcludedfromconsiderationinthis

section.Campbell75analyzedfourseriesofpatientsinwhich11examplesof
spontaneousclosureoccurredover1842patient-years,givingarateof0.6%per
annum.However,severaloftheexampleswerebasedonquitetenuousclinical
impressions.Innonewascatheterizationperformedbeforeandaftertheevent.


ThefigurecalculatedbyCampbellisalmostcertainlyanoverestimate.Hedid
notsuggestthatsurgeryshouldbedelayedexcept,perhaps,inpatientswith
smallshuntsandsignsthattheductwasalreadyclosing.Fewcardiologists
wouldnowagreeevenwiththeseexceptions.Thecapriciousnaturein
understandingwhetherspontaneousclosureiscommonhasbeennicely
summarizedrecentlybyJulienHoffman.76

EffectonLifeExpectancy
Bycombiningfourseries,consistingmainlyof“unselected”schoolchildrenwith
apersistentduct,Campbelldeducedamortalityrateof0.42%perannumduring
thefirst2decadesoflife.Thereafterhecalculatedmortalityratesperyearas1%
to1.5%inthethirddecade,2%to2.5%inthefourth,and4%foreach
subsequentyear.Thesecalculationsindicatethatone-thirdofpatientswitha
persistentductdiebytheageof40years,incontrasttolessthan5%ofthe
normalpopulation.Manyofthefiguresarebasedondataobtainedintheera
beforeantibioticswereavailable.Becauseinfectiveendocarditisisamajorcause
ofdeath,theimpactofantibioticsmustalsobetakenintoaccount.Thesefigures
agreefairlywellwithageatdeathasreportedinnecropsyseries.Forexample,
Abbott77foundthemeanageatdeath,havingexcludedthosewhodiedin
infancy,tobe30years,andinanotherseries,themeanagewas36.5years.78
Despitethisagreement,thefactremainsthatcalculationsfromautopsyseries,
andfromclinicalseries,areextrapolationsfromrathersmallnumbers.They
undoubtedlyexaggeratetheadverseaspectsofthenaturalhistory.

Complications
Theimportantcomplicationsofpersistentpatencyoftheductincludecongestive
heartfailure,infectiveendarteritis,pulmonaryvasculardisease,aneurysmal
formation,thromboembolism,andcalcification.

CongestiveHeartFailure
Congestiveheartfailureresultingfromanisolatedpersistentductdevelopseither
ininfancyorduringadultlife.Infectiveendarteritismayrarelyprecipitateheart
failureduringchildhood.Heartfailureininfancyusuallyhasitsonsetbeforethe
ageof3months.Adelayednormalfallinpulmonaryvascularresistancemay


causetheleft-to-rightflowtoincreaseprogressively.Theclinicalpictureis
initiallythatofleftheartfailure,withtachypneaandpulmonaryedema.
Ultimately,signsofrightheartfailureappearwithhepatomegaly.Although
initiallytheremaybeagoodresponsetodiuretics,thisisseldommaintainedand
closureisadvisable.Infantsbornattermdonotrespondtoindomethacinwhen
olderthan3months.Theoccasionaloccurrenceofsuddendeathininfants
treatedmedicallyfurtherencouragesapolicyofearlyintervention.Among
adults,thereusedtobeagroupwithcardiomegalyandfeaturesofleft
ventricularoverloadandstrain.Suchpatientsnowarerareincountrieswith
well-developedsystemsofhealthcare,becauseitisunlikelytheirlesionwould
haveescapeddetection.Congestiveheartfailuremayalsooccurasaterminal
eventinpatientsinwhomseverepulmonaryvasculardiseasecomplicatesa
persistentlypatentduct.Ifso,transcatheterclosureappearstobethetreatmentof
choice.

InfectiveEndarteritis
Infectiveendarteritisinapatientwithanuncomplicatedpersistentductis
uncommoninchildhood76andappearstobepreventedbysurgeryorcatheterbasedembolization.InSweden,overa33-yearperiodfrom1960,only2of3

milliondeathswereduetoinfectiveendocarditisandapatentarterialduct.79At
GreatOrmondStreetHospitalfrom1984to1996,therewereonlytwochildren
withductalendarteritisoutof17,887cardiacadmissionsandatNewcastle-onTyne,from92,093cardiacadmissions,onlyonecaseofinfectiveendocarditison
aduct.80Intheeraprecedingantibiotics,andinterventionalorsurgical
treatment,itwasamajorcauseofdeath,accountingforalmosthalfofalldeaths
inseveralpooledautopsyseries.77,78,81Campbell75calculatedaninfectionrate
ofbetween0.45and1.0%perannumforpatientsafterthefirstdecade.Thefirst
lineoftreatmentshouldbewithantibiotics,followingtherecommendationsas
establishedbytheAmericanHeartAssociation,withsurgeryorembolization
delayeduntilsterilizationiscompleted.Occasionally,thisprovesimpossible,in
whichcasesurgeryorocclusionshouldbeperformedundercontinuingantibiotic
therapy.82,83Vegetationsareusuallyfoundatthepulmonaryarterialendofthe
ductandmaygiverisetorecurrentpulmonaryembolization,withtheclinical
picturesuggestingrecurrentpneumonia.84Indevelopingnationswithlimited
accesstohealthcare,infectiveendarteritisassociatedwiththepersistentlypatent
ductcontinuestobeasignificanthealthissue.85Infectionmaycausesome