Intramitochondrial glycogen in hypertrophied infundibular muscle of patients with congenital heart diseases.

A small population of glycogen-containing mitochondria was found in operatively resected myocardium in 8 of 11 patients with various types of congenital heart diseases associated with right ventricular hypertrophy and muscular (infundibular) obstruction to right ventricular outflow. The presence of intramitochondrial glycogen correlated with the degree of peripheral arterial oxygen desaturation but not with the severity of hemodynamic alterations or with the ages of the patients. The occurrence of intramitochondrial glycogen in myocardium in other conditions is reviewed, and its possible pathogenesis is discussed.