Ultrastructural myocardial changes produced by viruses.

Some of the ultrastructural pathological alterations in the myocardium produced by viral infections with members of the picornavirus group are described. These alterations varied from mild to severe, with necrosis. In animals infected with Coxsackie B1 virus and EMC virus, readily identifiable viral crystals were frequently found in association with the myocardial lesions by means of electron microscopy. The electron microscope made it possible to study vary early myocardial changes which were not detected with the light microscope. Although the ultrastructural myocardial changes in rheumatic fever have received little attention, the light and electron microscopic findings in the myocardium and valves of the viral-infected animals described here closely resemble those described in man in association with so-called rheumatic heart disease. The type of investigations presented forms a good model for the study of the natural history of ultrastructural pathology produced in all parts of the heart by viruses.