On the possibility that a type of human muscular dystrophy commences in myocardium

Multicore myopathy: not always a benign entity

Four patients with Multicore Myopathy, a rare morphologically distinct myopathy, are described. Although previously considered to be a non-progressive or only slowly progressive myopathy, progression to significant disability was seen in three of our cases. The association of cardiac disease with Multicore Myopathy has not been previously emphasised. All four patients in this study had a cardiomyopathy, and heart disease was the cause of death in two of the patients. Multicore Myopathy is not always a benign entity. Cardiac involvement, when present, adversely affects prognosis.

Cardiac and skeletal myopathy associated with cardiac dysrhythmias

Electrophysiologic studies, echocardiograms, cardiac catheterizations and histologic and biochemical analyses of skeletal muscle biopsies were performed in 10 patients (aged 10 to 37 years, mean 21) who had dysrhythmias as the initial manifestation of cardiomyopathy. Presenting symptoms and signs attributable to dysrhythmias included sudden cardiac arrest in 2 patients, syncope in 3, presyncope in 3 and palpitations in 2. There was no clinical evidence of skeletal muscle weakness in any patient. Multicatheter electrophysiologic evaluation established diagnoses of ventricular tachycardia in 6 patients, primary atrial tachycardia in 2 and third degree infra-Hisian heart block in 1 patient. One patient presenting with palpitations had no inducible arrhythmia or conduction disturbance. Echocardiographic, angiographic and hemodynamic studies demonstrated previously unsuspected dilated cardiomyopathy in 7 patients and restrictive cardiomyopathy in 3. Skeletal muscle histologic characteristics were abnormal in all 10 patients; increases in lipid droplets and endomysial fibrosis were the characteristic findings. Serum free carnitine and short- and long-chain acylcarnitine were normal in 9 patients. However, skeletal muscle long-chain acylcarnitine was reduced in 9 patients. These findings support the concept that in certain patients presenting with dysrhythmias, the dysrhythmia may be a manifestation of cardiac and skeletal (that is, generalized) myopathy.

Neurogenic skeletal myopathy in patients with primary cardiomyopathy

Eleven patients with hypertrophic obstructive cardiomyopathy and eight patients with idiopathic congestive cardiomyopathy underwent extensive neuromuscular studies to determine if a skeletal myopathy is associated with uncomplicated primary cardiomyopathy. The clinical examination revealed peripheral neuropathies in six patients, but no evidence of muscle weakness or atrophy. Nerve conduction studies demonstrated a neuropathy in five of these six and in one other patient: three were in the hypertrophic group and three in the congestive group. Seven patients had abnormal electromyography, but none had characteristic myopathic changes. Of these seven patients, muscle biopsies showed denervation in two patients in the congestive group and type II atrophy in two patients in the hypertrophic group. We found no evidence of primary skeletal muscle involvement; however, neuropathic features and biopsy changes of denervation were present in both groups.

Cardiac biopsy in skeletal myopathy: report of a case with myocardial mitochondrial abnormalities

Transvenous right ventricular endomyocardial biopsy in an 11-yr-old boy with a proximal skeletal myopathy and a cardiomyopathy, has shown a major increase in mitochondrial size and numbers on electron-microscopic morphometry, with formation of unique ring-shaped mitochondria in cardiac muscle cells. The significance of this finding and the use of cardiac biopsy in children are discussed.

Myocardiopathy in Duchenne progressive muscular dystrophy

In a retrospective study of hospital and autopsy records of 19 male subjects with the Duchenne type of progressive muscular dystrophy the incidence of cardiac involvement of the heart almost invariably develop heart failure; an early sign may be persistent tachycardia and, possibly, electrocardiographic changes, in case of which institution of digitalis treatment should be considered. Cardiac and pulmonary complications were equally frequent causes of death (42%) but, death from cardiac complication occurred only patients with Duchenne progressive muscular dystrophy very often develop cardiac complications, and when relating the available information on treatment to the autopsy findings it should be stressed that early and intensive therapy of the cardiac symptoms is of the greatest importance to the patient.