Andersons pediatric cardiology 787
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pulmonaryvenouscongestion.Pulmonaryarterialhypertensionisreflectedbya
prominentpulmonaryarteryinolderpatients.
Rightventricularhypertrophyisalmostinvariablypresentonthe
electrocardiogram.ThefrontalmeanQRSaxisisusuallybetween+120and
+140degrees.Theremaybeevidenceofleftorrightatrialhypertrophyand
rarelyrightventricularhypertrophyifthereissignificantpulmonary
hypertension.
Cross-sectionalechocardiography(Fig.30.3)isthedefinitiveinvestigation,
permittingdirectvisualizationoftheobstructivepartitionandshowingthesiteof
interatrialdefects,ifpresent.1Thetechniqueshouldalsopermittherecognition
ofanyassociatedmalformations.Dopplerstudieshelpclarifythesituation.The
positionandsizeofthecommunicationbetweenthecompartmentsofthe
dividedatriumareoftenbestdelineatedbycolorflowmapping(Fig.30.4),while
spectralDopplerstudiesdefinethepressuredifferencebetweenthetwo(Fig.
30.5).Ifthereisanydoubtregardingthedispositionofthepulmonaryveinsor
otherassociatedabnormalities,cardiacMRImayhelprefinethediagnosis.
Invasiveinvestigationisnowrarelyperformedfordiagnosis,butassessmentof
pulmonaryarterypressureandresistancemaybeindicatedinadultswhenthere
isconcernforpossibleirreversiblepulmonaryhypertension,althoughthis
occurrencemustbeexceptionallyrare.
FIG.30.3 Cross-sectionalechocardiogramshowingthefeaturesofa
dividedleftatrium.
FIG.30.4 ColorflowmappinginthepatientshowninFig.30.3reveals
turbulentflowacrossthecommunicationbetweenthedistalandproximal
chambers.
FIG.30.5 SpectralDopplerrecordinginthepatientshowninFigs.30.3
and30.4revealsthevelocityofflowatthecommunicationbetween
