We report cases of acute death on exercise following the previous report and a method to diagnose the abnormal cardiac dynamics during exercise using radionuclide. Autopsy data of 42 death cases on exercise from 1975 to 1980 were summarized from data reported by Japanese association of safety assurance in school and university.
　A hypoplasia of cardiovascular system was the most frequent finding. A hypertrophy of thymus, hypoplasia of adrenal gland, idiopathic cardiomyopathy and myocarditis were common too. In 3 cases of acute death recently occurred in Tokyo University, 2 cases showed hypoplasia of heart, aorta and adrenal gland. To diagnose abnormal cardiac dynamics on exercise in such abnormalities, multigated radionuclide angiography was developed by us. This method is able to analyze left ventricular endosystolic (ESV), endodiastolic volumes (EDV) and left ventricular ejection fraction using in vivo red blood cell labelling method. In normals, the ESV decreased, the ejection fraction (EF) and cardiac index (CI) increased as the intensity of exercise increased. But in impaired heart, the EDV and ESV increased, EF decreased and the increase of CI became smaller.
　This method is able to diagnose the lowering of cardiac function in failing heart on exercise. It may be a useful strategy to prevent cardiac accident on exercise in asymptomatic heart disease.

DESCENTE SPORTS SCIENCE Vol.2/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE