Cardiovascular Imaging

Cardiomyopathy, hypertrophic

disease of the myocardium causing inappropriate hypertrophy. The left ventricle is invariably involved and the right ventricle also involved infrequently. The hypertrophy is most often asymmetric, involving the ventricular septum but sometimes symmetric involving the entire left ventricle. Variant forms disproportionately involve the middle or apical region of the left ventricle. The apical form has been reported frequently in Japan. There is a genetic predisposition to the disease. The severity of the disease among family members is highly variable. The disease nearly always causes diastolic dysfunction with reduced ventricular compliance and in some cases also causes subaortic obstruction and mitral regurgitation.

The chest X-ray is usually normal; however, pulmonary venous hypertension may be present. Cardiomegaly with left atrial enlargement may reflect significant mitral regurgitation. Echocardiography, either M mode or two-dimensional, establishes the diagnosis and is used to detect occult cases in relatives of patients who are known to be affected. Echocardiography demonstrates ventricular wall thickening, usually greater than 15 mm, and systolic anterior motion of the anterior leaflet of the mitral valve. Doppler colour flow mapping demonstrates the presence and severity of mitral regurgitation. Doppler echocardiography can also be used to estimate the subaortic pressure gradient. Left ventricular angiography demonstrates a hypercontractile left ventricle with cavity obliteration; abnormal shape of the left ventricle; systolic anterior motion of the mitral valve; subaortic obstruction caused by systolic apposition of the anterior mitral leaflet with the hypertrophied ventricular septum; and mitral regurgitation. Obliteration of the middle or apical portion of the left ventricle is characteristic for the mid-ventricular and apical forms, respectively. Coronary arteriography frequently shows reciprocating flow with systolic compression of the septal branches of the left anterior descending artery. MRI is the best technique for demonstrating the distribution of the hypertrophy in the two ventricles and for quantifying the ventricular mass (Fig.1).

CBH

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Fig.1

ECG-gated spin-echo image in coronal plane demonstrates severe symmetrical hypertrophy of the left ventricle.
Cardiomyopathy, hypertrophic, Fig.1