Secondary endocardial fibroelastosis associated with Pompe disease and multicystic dysplastic kidney.

An infant with secondary endocardial fibroelastosis (EFE) associated with glycogen storage disease II (Pompe disease) and multicystic dysplastic kidney (MCDK) is described. She had had refractory heart and renal failure from the early neonatal period. In spite of administration of cathecholamines and diuretics, ventilator support, and peritoneal dialysis, her heart failure due to reduction of left ventricular contractility progressively worsened. She died on the 40th day after admission. Histological examination of a left ventricular autopsy specimen showed prominent thickening of the endocardium due to fibroelastosis, and a lacework-like structure due to accumulation of glycogen in the cardiomyocytes. The EFE was derived from degeneration of the smooth muscle in the endocardium and cardiomyocytes due to glycogen storage. In addition, we supposed that the renal failure due to MCDK made the preload for the ventricles increase and accelerated her heart failure.