[Hypertrophic and/or obstructive primary cardiomyopathies: genetic, etiologic, physiopathologic aspects]

The morphological features, mode of presentation and physiopathology of hypertrophic cardiomyopathy (HCM) are variable. Autosomal dominant seems to be the usual mode of transmission but with variable presentation. From the anatomical point of view, the hypertrophy is asymmetrical with septal predominance. The main histological features are myocytic architectural disorganisation, fibrosis and abnormal coronary arteries of small diameter. Ventricular hyperkinesis is usually present and sometimes associated with outflow obstruction, the physiological role and mechanisms of which are still not fully understood. On the other hand, abnormal diastolic function is frequently observed, and, quite independently of disease of the epicardial coronary arteries, ischaemic phenomena may occur. Although the biological substrate of HCM is unknown, abnormalities of the adrenergic system and transmembrane calcium flux probably play a part in the expression of the disease.