Restrictive cardiomyopathy in children. Ultrastructural findings.

Restrictive cardiomyopathy is usually related to fibrosis of the endocardium or to an infiltrative disorder. However, in few cases, it can be due to isolated pathology of the myocytes but such alterations are not well characterized. This paper reports the disease in two 7 year old patients. There was severe venous congestion and catheterisation revealed increased end diastolic pressure in the ventricles. Both pericardial and myocardial biopsies were performed, as the clinical and haemodynamic data were indistinguishable from constrictive pericarditis. The structure of the pericardium was normal. The endocardium was not thickened. The interstitium of the myocardial tissue was not increased. Electron microscopic examination revealed intracellular masses of disorganized myofilaments. These large deposits may have produced decrease compliance of the myocytes and of the ventricular walls.