Andersons pediatric cardiology 1350
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ClinicalFeatures
Thepresentationusuallyisintheneonatalperiodorearlyinfancy,similartothat
ofpatientswithlargeleft-to-rightshuntssuchaslargearterialductsorVSDs.
Clinicalsignsandsymptomsappearinthefirstfewweeksormonthsoflifeand
includetachypnea,sweatingwithfeedings,poorfeeding,failuretogainweight,
andincreasedrespiratoryinfectionssecondarytopulmonaryovercirculationas
thepulmonaryvascularresistancefalls.Cyanosisisunusualinearlyinfancyand
suggestselevatedpulmonaryvascularresistancewithbidirectionalshunting.
Physicalexaminationdemonstratestachypnea,boundingpulses,andasystolic
murmurheardalongtheleftsternalborder.Amitralrumbleiscommoninthe
settingofalargeleft-to-rightshunt.WhenanAPwindowisassociatedwith
interruptedaorticarch,neonatalpresentationwithweakfemoralpulsesand
shockcanoccurduetoductalconstriction.Pulmonaryhypertensionisafrequent
latecomplicationinuncorrectedlargeAPwindow,inwhichthereisreversalof
flowfromthePAtotheaortawithfeaturesofEisenmengersyndrome,including
cyanosisandclubbing.
Investigations
Antenataldiagnosisisuncommonbecausetheremaybeminimalidentifiable
flowacrossthedefectduetoequalpressuresintheascendingaortaandPAinthe
fetallife.Still,inthecurrentera,severalcasesofprenataldiagnosisofAP
windowhavebeenreported.Recentreportshavedemonstratedincreased
accuracyofprenataldiagnosis.TheAPwindowmaybebestvisualizedinthe
three-vesselviewlocatedbelowthebifurcationoftherightPAandthehigh
short-axisviewofthegreatarteries(doughnutview)withcephalad
angulation.20–22Afterbirth,theelectrocardiogrammayshowfeaturesofright
andleftventricularhypertrophyandtachycardia,andthechestx-raycanshow
cardiomegalyandincreasedpulmonaryvascularmarkingsinpatientswith
pulmonaryovercirculation.Thediagnosisiseasilyconfirmedwithtwodimensionalechocardiography;identifyingtwoseparatesemilunarvalvesin
parasternallongandshort-axisviewsexcludescommonarterialtrunk.TheAP
windowisbestviewedinhighparasternalshort-axisviewwiththetransducer
tiltedsuperiorly(Fig.51.9).Completeevaluationtoruleoutadditional
anomalies(e.g.,presenceofanarterialductinassociationwithinterruptedaortic
arch,ortetralogyofFallot)isessential.ColorDopplercanbehelpfulin
confirmingflowthroughtheAPwindow.Cardiaccatheterizationiscurrently
rarelyrequiredforthediagnosisofanAPwindowininfancy.Catheterizationis
reservedforpatientswhopresentinlaterinfancyandchildhoodwithpulmonary
vasculardisease,inwhichcasepulmonaryvasodilatortestingisperformedto
determinereactivityofthepulmonaryvascularbed.Aortographyinthe
anteroposteriorandlateralprojectionscanusuallydemonstratethewindow.Itis
essentialtoevaluatecoronaryarterialanatomypreoperativelyandavoidmissing
anomalousoriginofeithercoronaryarteryfromthepulmonarytrunkbecause
thisisassociatedwithpooroutcomes.23Magneticresonanceimaging(MRI)or
multislicecomputedtomography(CT)maybeusefulinthisregard.
