Andersons pediatric cardiology 2024
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Typically,thecentralpulmonaryarteriesareenlarged,andtheremaybe
cardiomegaly.Inaddition,therearediminishedperipheralpulmonaryvascular
markings.Thepresenceofincreasedinterstitialmarkingsorpulmonaryedema
shouldpromptawork-upforinterstitiallungdisease,pulmonaryvenous
obstruction,orleftheartdiseaseasanetiologyofpulmonaryhypertension.
Electrocardiogram
Theelectrocardiogrammaybenormalinaminorityofpatients.Inmostpatients
theelectrocardiogramdemonstratesrightaxisdeviation,rightatrialenlargement,
and/orrightventricularhypertrophy,butthesensitivityandspecificityarelow.
Biomarkers
Themostcommonlyusedbiomarkerduringevaluationofpulmonary
hypertensionisb-typenatureticprotein(BNP)orNT-proBNP.Theseare
releasedbytherightandleftatriuminresponsetovolumeoverloadandstretch.
Theyarenotspecificbuthavebeenshowntocorrelatewithprognosis.In
isolation,BNPvaluesarelikelynotusefulbutmaybeausefulmarkertotrend.62
Six-MinuteWalkTestandExerciseTesting
The6-minutewalktestisasubmaximalexercisetestandhasbeenusefulin
adultswithmoreseverepulmonaryhypertensionbecausepretreatmentresults
correlatewithsurvival.Thetestisusefulforlongitudinalfollow-upandto
monitorresponsetotreatment,althoughimprovementsinwalkdistancedonot
correlatewithsurvival.Thetestiseasytoperformandhasbeenusedasanend
pointinprospectiveclinicaltrials.Thelimitationsofthetestincludelimited
utilityinpatientswithlessseveredisease,subjectivenature,andthatpatient
motivationandcooperationcangreatlyaffectresults.63Inpatientswithless
severedisease,serialcardiopulmonaryexercisetestingisuseful.
Echocardiography
Echocardiographyisoneofthemostimportanttoolsforscreeningand
diagnosingpulmonaryhypertension.Signsofpulmonaryhypertensioninclude
rightatrialandventricularenlargement,possiblywithdecreasedrightventricular
function(Videos75.1and75.2).Dopplerechocardiographyallowsestimating
therightventricularsystolicpressurebyassessingthetricuspidregurgitant
velocity.However,manypatientsdonothavedetectabletricuspidvalve
regurgitationorpulmonaryinsufficiency,andthusechocardiographymaymiss
significantpulmonaryhypertension.Otherindirectsignsofpulmonary
hypertensionareaflattenedorparadoxicalventricularseptumduringsystole(the
eccentricityindexisasurprisinglyaccuratesurrogateofrightventricular
pressureelevation),inferiorvenacavadilation,andcollapse.Echocardiography
isveryimportanttoruleoutstructuralheartdiseaseastheetiologyofpulmonary
orrightventricularpressureelevation.Anassessmentofrightventricular
functionshouldalsobeobtained.TissueDopplerimagingisabletodemonstrate
abnormaldiastolicandsystolicrightventricularfunction,aswellasleft
ventriculardiastolicfunction.Recentadvancementsinechocardiographyhave
increasedtheavailabletoolstomeasurerightventricularperformance.Those
withhighestdiagnosticaccuracyincludespeckletrackinggloballongitudinal
strainandrightventricularfreewallstrain.Tricuspidannularplanesystolic
excursionhasalsobeeninvestigatedwithlessdiagnosticaccuracy.64
MagneticResonanceImaging
Cardiacmagneticresonanceimaging(MRI)isthegoldstandardforevaluation
ofrightventricularperformance.65Phase-contrastmagneticresonance
measurementsofflowinthepulmonarytrunkcorrelatewithhemodynamic
changes,andtheaveragevelocitythroughoutthecardiaccircleappearstomirror
thepulmonarypressuresandresistance.66Inpatientsclinicallyknowntohave
pulmonaryhypertension,thecardiacMRIratio–derivedleftventricularseptalto-freewallcurvaturewasanaccurateandreproducibleindexforestimationof
rightventricularsystolicpressureifcomparedwithmeasurementatrightheart
catheterization.67SeveralMRI-derivedparametersincludingvolume,stroke
volumes,andrightventricularejectionfractionshavebeenassociatedwith
mortalityinpulmonaryhypertensioninadults.68Thesefindingsneedtobe
validatedinthepediatricpopulation,butcardiacMRIisanimportantmonitoring
toolofrightventricularfunction.
CardiacCatheterization
Catheterizationoftherightheartremainsthegoldstandardfordiagnosisof
pulmonaryhypertension,buttheprocedureforpatientswithadvanced
pulmonaryvasculardiseaseisassociatedwithsignificantmortalityand
morbidityrisks.Catheterizationinpatientswithseverepulmonaryhypertension
shouldbeperformedonlyincentersexperiencedwiththemanagementof
pediatricpulmonaryhypertension.Thegoalofinitialcatheterizationisto
confirmthediagnosis,assesstheseverityofdisease,assessresponsivenessto
vasodilators,andexcludeotherpotentialtreatablediagnoses.Subsequent
catheterizationsareusefultomonitordiseaseprogression,responsetotherapies,
andassesscandidacyforlungorheart-lungtransplantation.Astandardright
heartcatheterizationshouldbeperformedwithcarefulassessmentofrightatrial
pressure,pulmonaryarterialpressures,pulmonarycapillarywedgepressure,and
systemicbloodpressure.Ifthepulmonarycapillarywedgepressureisunusually
highorlow,directmeasurementofleftventricularpressuresareimportantin
assessingforpulmonaryvenousobstruction.Measurementofsystemicand
pulmonarybloodflowsshouldbeperformed.
Acutevasoreactivitytestingisanimportantcomponentofcatheterizationto
assesscandidacyforuseofcalciumchannelblockingmedicationsandfor
prognosis.Thedefinitionofaresponderinadultswithisolatedpulmonary
hypertensionincludeafallinpulmonaryarterypressuretolessthan40mmHg
andeitherpreservedorincreasedcardiacoutput.Analternativedefinitionisa
fallinmeanpulmonaryarterypressureby20%withpreservedorincreased
cardiacindexandpreservedordecreasedpulmonaryvascular
resistance/systemicvascularresistanceratio.Agentsusedfortestinginclude
inhalednitricoxide,intravenousadenosineorsildenafil,orinhaled
prostacyclins.Thenumberofchildrenwhoareresponsivetovasodilatorsvaries
intheliterature,witharangeof10%to30%.
LungBiopsy
Thisprocedureisrarelyindicatedinthemodernera.However,biopsymaybe
essentialindiagnosingvasculitis,pulmonaryvenoocclusivedisease,or
pulmonarycapillaryhemangiomatosis.69Themostimportantlimitationofan
openlungbiopsyisthehighriskofmortalityduringanesthesiaandthesurgical
procedure.
GeneticTesting
