[The myocardiopathies of hereditary neuro-muscular diseases]

Abstract

This joint work has studied the cardiomyopathies occurring in hereditary neuro-muscular disorders (270 cases). The Duchenne type of disorder (74 cases) was responsible for asystole (4 cases), for cardiomegaly, and especially for abnormalities of the ECG (59 cases)--Q waves and large R waves in V1 and V6. The cardiomyopathy was of the hypokinetic type, with histological evidence of degeneration of the myocardial fibres. Dystrophia myotonica of Steinart (23 cases) caused conductive disorders (17 cases) which were either atrioventricular or intra-ventricular or both. Studies of the His pathway confirmed that these abnormalities were more diffuse in 5 cases. The main histological feature was interstitial fibrosis. There was a high risk of sudden death; ECG follow-up should be close. Friedreich's disease (20 cases) in its complete form led to later development of obstructive cardiomyopathy, with a systolic ejection murmur, cardiomegaly, and abnormalities of the ECG--left ventricular hypertrophy in the vertical axis, right ventricular and septal hypertrophy, repolarisation disorders similar to those found in coronary artery disease. Histology showed hypertrophy with degeneration of the myocardial fibres and interstitial fibrosis. This complete form was rare (7 cases out of 20); on the other hand, ECG abnormalites were very common (16 cases out of 20). The authors have tried to study the relationships between primary cardiomyopathies (50 cases) and peripheral neuromuscular disorders. 17 of the 39 peripheral muscle biopsies were abnormal, but a well-defined muscular dystrophy could not be found in them.