Andersons pediatric cardiology 1076

HistoricalConsiderations
WhenSiegal1reexaminedtheoriginalsecondcenturyGreektextofGalen,he
pointedoutthatGalenwasfamiliarwithmanyaspectsofthefetalcirculation
eventhoughhedidnotrealizethatbloodcirculated.Galenunderstoodthatfetal
bloodwasaeratedintheplacentaandthatbloodwasdivertedawayfromthe
liverbyashortvesselconnectingtheportaltotheinferiorcavalvein.Healso
knewthatbloodpassedthroughtheovalforamentobypasstherightventricle
andreachtheleftsideoftheheartdirectly.Herealizedthatsomebloodstill
enteredtherightventricleandpulmonarytrunk,fromwhenceitwasshuntedinto
theaortathroughaspecialfetalchannel,therebybypassingthelungs.The
quotationatthebeginningofthischapter,takenfromSiegal,1providesaclear
indicationofGalen'sunderstandingofthedramaticreadjustmentofthe
circulationatbirth.
Nevertheless,Botalloisthenameweusuallyassociatethepersistentlypatent
arterialduct.Infact,Botallodescribedpostnatalpatencyoftheovalforamen!It
wasbyaseriesofmisinterpretationsandcarelesstranslationsthathisname
becamequiteunjustifiablyattachedtothearterialduct2;theattributionofthe
discoveryshouldmoreaccuratelybecalledanindependentrediscovery.3
WilliamHarvey,whowasapupilofFabrizid'AcquapendenteinPadovafor2
years,synthesizedpreviousdetaileddescriptionsoffetalcardiacanatomyfrom
hismentorinhisownwritings.Hisgeniusresidedinproposingtheconceptof
activecirculationoftheblood.Hewaswellawareofthelargesizeofthearterial
ductpriortobirthandthefactthatbloodflowedthroughitfromrighttoleft
duringfetallife.4Harvey4wasincorrectonlyinhisbeliefthatflowofbloodto
thelungswascompletelylackinginthefetus.Subsequently,Highmore,afriend
ofHarvey,describedclosureofboththeovalforamenandthearterialductas
occurringwiththeonsetofrespiration,believingthearterialducttocollapseasa
consequenceofbloodbeingdivertedtothelungs.5Sincethen,severalingenious
theorieshavebeenputforwardtoexplainclosureoftheduct,allbeingbasedon
postmortemappearancesandallinvokingmechanicalfactors.6Virchow7first
suggestedthattheclosureresultsfromcontractionofitsmuralsmoothmuscle,

andGerard8introducedtheconceptoftwo-stageclosure,inwhichfunctional
constrictionisfollowedbyanatomicobliteration.ThankstoHuggett,9wecame
tounderstandtheroleofoxygenincausingfunctionalclosurebymuscular


contraction.
Asearlyas1907,inanaddresstothePhiladelphiaAcademyofSurgery,John
Munrohadsuggestedsurgicalligationofthepersistentlypatentarterialduct.10
Afteranintervalof31years,thefirstattemptatsurgicalclosurewasmadeina
22-year-oldwomanwithbacterialendocarditis.11Unfortunately,althoughthe
patientsurvivedthesurgery,shediedafewdayslaterfromcomplicationsofthe
infection.Asaresult,RobertGrossofBostonfirstsuccessfullyligatedapatent
ductina7-year-oldchildwithintractableheartfailure.12Hetherebyintroduced
anamazingeraofprogressinthesurgeryofcongenitalmalformationsofthe
heart.Nohistoricalreviewofthearterialduct,howeverbrief,wouldbecomplete
withoutrecognizingtheimportanceofGibson'sexquisitedescriptionofthe
murmurthattypifiesitspersistence,13notwithstandingthefashioninwhich
Gibson'sinitialaccounthassubsequentlybeenmisquoted.14


Nomenclature
Fromtimetotime,authorshavearguedthattheterms“patent”or“persistent”
areredundanciesthatshouldbeavoidedwhendescribingthearterialduct.Inour
view,thisoversimplifiesthesituation,andbothtermsretaintheirvalue.
Persistenceimpliesthattheductispresentafterthetimeofitsexpectedclosure
andthereforedistinguishesapathologicfromaphysiologicstate.Theconceptof
patencyremainsusefulintheperinatalperiod,especiallyintheprematureinfant
inwhomthetermcanbeusedtosignifyaductthatisfunctionallyopen,as
opposedtoonethatisfunctionallyclosedbutretainsthepotentialtoreopen.