Andersons pediatric cardiology 1651
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midsystolicclosureoftheaorticvalve.Thedegreeofobstructionmaybe
quantifiedusingpulse-waveandcontinuous-waveDopplermeasurements.The
dynamicnatureofobstructioninHCMmaybereflectedinDoppler
measurementsandunderscorestheimportanceofexercisestress
echocardiographyinpatientswithamaximumpeakoutflowtractobstruction
lessthan50mmHgwhoarepersistentlysymptomatic.7
FIG.61.4 Echocardiographicfeaturesofleftventricularoutflowtract
obstruction.(A)M-modetracingoftheaorticvalvefroma5-year-oldwith
severeobstructivehypertrophiccardiomyopathywithcoarseflutteringand
midsystolicclosureoftheleaflets.(B)M-moderecordingofthemitralvalve
froma12-year-oldwithhypertrophicobstructivecardiomyopathyshowing
completesystolicanteriormotionoftheaorticmitralvalvarleaflet.
MitralvalveinsufficiencyoccursinthemajorityofpatientswithHCMand
LVOTO.Theinsufficiencyistypicallyposteriorlydirectedandoccurssecondary
tosystolicanteriormotionofthemitralvalveinalmostallpatients.240Although
mitralvalveabnormalitiesarecommoninHCM,themajorityofpatientsdonot
requiremitralvalverepairorreplacementandregurgitationwilltypically
improvewithmyectomyandreliefofoutflowtractobstruction.202,203,240,241
PatientswithHCMwilltypicallyhaveevidenceofdiastolicdysfunctionon
echocardiography(Fig.61.5).214,219Thechronicelevationofleftventricular
fillingpressurestypicallyleadstoleftatrialenlargementandremodeling,which
areriskfactorsforadversecardiovascularoutcomesovertime.42,214,220–223
FIG.61.5 Echocardiographicfeaturesofleftventriculardiastolic
impairment.(A)Pulsed-waveDopplertracingofthemitralinflowfroma7year-oldwithhypertrophiccardiomyopathyshowingE/A-wavereversaland
aprolongedE-wavedecelerationtime,characteristicofimpairedrelaxation
oftheleftventricle.(B)Anotherpulsed-waveDopplerrecordingofa15year-oldshowingpseudonormalizationofthepatternofmitralinflow,witha
normalE/AratiobutprolongedE-wavedecelerationtime.(C)Pulsed-wave
Dopplerrecordingintherightupperpulmonaryveinfroma14-year-oldwith
severehypertrophiccardiomyopathyshowingimpairedrelaxationoftheleft
ventricle,characterizedbyareduceddiastolicwaveandincreasedatrial
reversalwave.(D)Pulsed-wavetissueDopplerrecordingofthelateral
mitralannulusina13-year-oldwithhypertrophiccardiomyopathyshowing
reducedsystolic,earlydiastolic,andlatediastolicvelocities.
CardiacMagneticResonanceImaging
Cardiacmagneticresonanceimaging(CMRI)maybeusedtoassesscardiac
anatomyandmyocardialfibrosisinpatientswithknownorsuspected
HCM.6,28,242CMRIallowsthedetectionofhypertrophy,whichmaynotbe
appreciatedbyechocardiography,especiallyinthesettingoflimited
echocardiographicwindows.28CMRIalsoallowstheassessmentofmyocardial
fibrosis,whichisevolvingasariskfactorforarrhythmiaandadverseoutcomes
inadults(Fig.61.6).228,243–246
FIG.61.6 Lategadoliniumenhancementwithintheventricularseptumof
a16-year-oldwithhypertrophicobstructivecardiomyopathy.
CardiopulmonaryExerciseTesting
ReducedactivitytoleranceiscommoninpatientswithHCMandisthoughttobe
multifactorialinnature.Diastolicdysfunction,LVOTO,microvascular
abnormalities,andsystolicdysfunction(inend-stagedisease)arethoughttobe
contributory.247,248Althoughtherearefewdataoncardiopulmonaryexercise
testinginchildren,decreasedpeakmaximaloxygenconsumptionisrelatively
commoninadultswithHCMandisassociatedwithadverseclinical
