Hypertrophic cardiomyopathy echocardiography
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Editors-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Echocardiography is the imaging modality of choice in the diagnosis of hypertrophic cardiomyopathy. Classically there is a small left ventricular cavity with hypertrophy out of proportion to any underlying condition that would cause LVH. The hypertrophy is often asymmetric.
Echocardiography
Echo with doppler is the primary procedure used to diagnose hypertrophic cardiomyopathy. There is a prolonged isovolumic relaxation time, reduced peak E velocity, prolonged deceleration time, increased peak A velocity, and decreased E/A ratio as compared to normal controls.
Proper examination should evaluate [1]:
- Left ventricular asymmetric hypertrophy
- Parasternal long axis shows relationship of the septal hypertrophy and the outflow tract
- Left ventricular diastolic dysfunction
- LV inflow across the mitral valve
- LA inflow in the pulmonary vein
- Myocardial Doppler tissue velocity
- Isovolumetric relaxation time
- Dynamic outflow tract obstruction
- SAM (systolic anterior motion) of the mitral leaflet
- Mid-systolic closure of the aortic valve
- Late peaking, high velocity flow in the outflow tract
- Variability of obstruction with maneuvers (exercise, amyl nitrate inhalation, and post-PVC beats)
- Doppler Techniques
- Use continuous wave doppler to measure the systolic flow velocity in the LV outflow tract and mid-cavity (both at rest and during maneuvers such as the Valsalva maneuver or during dobutamine administration.
Because of the turbulent, high-velocity jet in the left ventricular outflow tract (LVOT), the anterior mitral leaflet moves anteriorly in systole, exacerbating the outflow tract obstruction, and promoting mitral regurgitation. The following images show classic systolic anterior motion (SAM) of the mitral valve leaflets:
On parasternal long-axis view
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On parasternal short-axis view
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Frequency of Hypertrophy
While LVH is usually present, not all carriers with HCM demonstrate left ventricular hypertrophy. Left ventricular hypertrophy may be absent in childhood. It may then appear following the rapid growth of adolescence and may first appear at age 17 to 18[2][3][4].LVH may be time dependent and may appear late, particularly in patients with a mutation in the myosin-binding protein C gene. Patients generally present later in life and in general, have a better prognosis than beta myosin heavy chain or cardiac troponin T mutations. Up to 60% of patients at age 50 years have no evidence of LVH. LVH may appear later in life in these patients. Because of this, a normal EKG and a normal ECHO at maturity does not exclude the presence of an HCM mutation [5].
Diagnostic Features of Hypertrophy
- Left ventricular hypertrophy (LVH) most often in an asymmetric distribution,
- Thickening of the left ventricular wall in the absence of cavitary dilation and the presence of hyperdynamic activity (in fact there may be systolic cavity obliteration or near obliteration)
- Absence of any other cause of left ventricular hypertrophy such as aortic stenosis or hypertension
Left Ventricular Wall Thickness
- The traditional definition requires a wall thickness > 15 mm.
- Borderline wall thicknesses of 13-14 mm must be distinguished from extreme variants of athletes heart
- There are some genetic variants that yield a normal wall thickness [6][7][8][9][10].
- Among children < 13 years of age, LVH is often absent.
References
- ↑ Otto, Catherine. Textbook of Clinical Echocardiography. 3rd Edition, 2004
- ↑ Hagege AA, Dubourg O, Desnos M et al. Familial hypertrophic cardiomyopathy. Cardiac ultrasonic abnormalities in genetically affected subjects without echocardiographic evidence of left ventricular hypertrophy. Eur Heart J 1998;19:490–9.
- ↑ Maron BJ, Spirito P, Wesley Y, Arce J. Development and progression of left ventricular hypertrophy in children with hypertrophic cardiomyopathy. N Engl J Med 1986;315:610–4.
- ↑ Spirito P, Maron BJ. Absence of progression of left ventricular hypertrophy in adult patients with hypertrophic cardiomyopathy. J Am Coll Cardiol 1987;9:1013–7.
- ↑ Erdmann J, Raible J, Maki-Abadi J et al. Spectrum of clinical phenotypes and gene variants in cardiac myosin-binding protein C mutation carriers with hypertrophic cardiomyopathy. J Am Coll Cardiol 2001;38:322–30.
- ↑ Niimura H, Bachinski LL, Sangwatanaroj S et al. Mutations in the gene for cardiac myosin-binding protein C and late-onset familial hypertrophic cardiomyopathy. N Engl J Med 1998;338:1248–57.
- ↑ Maron BJ, Niimura H, Casey SA et al. Development of left ventricular hypertrophy in adults in hypertrophic cardiomyopathy caused by cardiac myosin-binding protein C gene mutations. J Am Coll Cardiol 2001;38:315–21.
- ↑ Charron P, Dubourg O, Desnos M et al. Diagnostic value of electrocardiography and echocardiography for familial hypertrophic cardiomyopathy in a genotyped adult population. Circulation 1997; 96:214–9.
- ↑ Charron P, Dubourg O, Desnos M et al. Diagnostic value of electrocardiography and echocardiography for familial hypertrophic cardiomyopathy in genotyped children. Eur Heart J 1998;19:1377–82.
- ↑ Panza JA, Maron BJ. Relation of electrocardiographic abnormalities to evolving left ventricular hypertrophy in hypertrophic cardiomyopathy during childhood. Am J Cardiol 1989;63:1258–65.