Coxsackie viral infection of human myocardium

The myocardiu m of a young patient who had clinically established cardiomyopathy and suspected Coxsackie virus B4 infection was studied. Coxsackie B4 viral antigen was found in the ventricular and atrial myocardium by specific immunofluorescent antibody staining. Histologic examination revealed varying degrees of myocardial damage. Interstitial fibrosis and edema, swelling and deterioration of hypertrophic muscle fibers, connective tissue proliferation, stasis of small coronary blood vessels, atrophy of myocardial fibers with pyknosis of nuclei, and lytic deterioration were observed. Electron microscopic examination showed portions of the Z bands to be either widened or displaced into the sarcomere. Adjacent cell membranes in the region of the intercalated disc in the myocardium of both the ventricle and the atrium were separated, forming large gaps. Morphologic changes were most pronounced in the atrium adjacent to the mitral valve, in which the mitochondria were grossly swollen, and large vesicles were present in the sarcoplasm. The pathologic changes found in the myocardium of all chambers of the heart apparently were due to Coxsackie B4 viral infection.