Histologic and ultrastructural features of primary and secondary endocardial fibroelastosis.

The average size of elastic fibers in thickened left ventricular endocardium was much larger in four patients with congenital endocardial fibroelastosis (EFE) than in six patients with acquired EFE (secondary to ischemic heart disease in two patients, to prosthetic cardiac valves in three, and to irradiation of the chest in one). Both components of normal elastic tissue (central, amorphous cores, and peripheral microfibrils) were present in endocardial elastic fibers of each patient. Ultrastructural identification of elastic fibers was greatly facilitated by staining with silver tetraphenylporphin sulfonate.