We examined the rates of sudden death to ordinary deaths of the patients in two hospitals in Obihiro. A total of 130 sudden death cases (89 men and 41 women) out of 1, 088 ordinary deaths were listed (11.9%) during the period of two years from 1992 through 1993.
We also looked into the cause of sudden death in 86 autopsied cases over a 15-year period from 1985 through 1999 from a pathological stand point. Cardiac diseases underlay 49 cases of sudden death. Myocardial infarction (42 cases), cardiomyopathy (2), sarcoidosis (1), amyloidosis (2) and valvular disease (2) were regarded as the causes of death in the 49 cases. Myocardial infarction occurred more frequently in men than in women (27: 15). Next to cardiac diseases came aortic diseases such as ruptured aortic aneurysm (7 cases) and dissecting aneurysm (6). Cardiac diseases (49 cases) and aortic diseases (13) combined to account for 62 of 86 (72.1%) autopsied cases. Among noncardiovascular diseases, respiratory diseases (18 cases) topped the list, followed by alimentary diseases (3) and cerebral bleeding (2). The major cause of respiratory diseases was pulmonary embolism (16). Pulmonary embolism more often occurred in women than in men (14: 2). There was one case of unidentifiable sudden death, namely Pokkuri disease. A decreased incidence of sudden death on Sunday should be noted. A circadian rhythm was evident. The incidence of sudden death started rising from 6: 00 and peaked at 15: 00. Sudden death occurred during rest (42 cases), during routine daily activity (14), during sleep (11), during bathing (1), during defecation (8), during surgery (2), during physical exercise (6) and during agricultural work (2).