Hypertrophic
Cardiomyopathy
Epidemiology and
Etiology:
- Causes:
- idiopathic
- genetic
(AD mostly) (mostly single-point missense
mutations)
- Beta-myosin
heavy chain most frequent (~35%)
- Myosin-binding
protein C (~15%)
- Troponin T (~15%)
- Alpha-tropomyosin (< 5%)
- Myosin
light chain (<1%)
- Friedreich ataxia
- Storage
diseases
- Infants
of diabetic mothers
Common sites:
Gross features:
- Disproportionate
thickening of the ventricular septum as compared with the free wall of
the left ventricle (90%)
- Ratio
> 1:3
- Usually
most prominent in subaortic location
- Symmetrical
hypertrophy throughout the heart (10%)
- Ventricular
cavity compressed into a “banana-like” configuration
- Endocardial thickening of the left
ventricular outflow tract
- Thickening
of the anterior mitral leaflet
Histologic
features:
- Extensive
myocyte hypertrophy to a degree unusual in
other conditions
- Transverse
myocyte diameters frequently > 40 um
(normal ~ 15 um)
- Haphazard
disarray of bundles of myocytes, individual myocytes, and contractile elements in sarcomeres within cells
- Interstitial
and replacement fibrosis
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- clinical
features:
- LVEF
50-80% (systolic function preserved)
- Diastolic
heart failure
- Anginal pain
- Atrial fibrillation
- Complications:
- Mural
thrombus formation (atrial fibrillation)
- Infective
endocarditis of the mitral valve
- Intermittent
ventricular outflow obstruction (33%)
- Intractable
cardiac failure
- Ventricular
arrhythmias
- Sudden
death
References: