Rupture of the infarcted interventricular septum was first described more than a century ago in this country (Latham, 1846). The subject was last reviewed by Fowler and Failey (1948), who discovered 56 recorded cases, of which 16 were diagnosed during life. Since their review, single cases have been described by Sweeny (1948), Bickerman and Irons (1949), Shapir (1949), Ungar and Ullman (1950), and Muller et al. (1950) and two by Furman and Meneeley (1948). All of these were diagnosed during life. Thus, until the time of writing, 23 out of 63 cases were correctly diagnosed before death. A further example in which a diagnosis of ruptured septal infarction was made, before death, is recorded here.The physical signs were noted in 51 of these cases. In 49 there were systolic murmurs, with associated thrills in 24. In 4 there were diastolic murmurs, in 2 there were no abnormal auscultatory signs to suggest the lesion, and in the remaining 13 the physical signs were not recorded.Case Report A man, aged 72, was admitted to hospital in February, 1950. He had served in the Royal Navy from twenty until hd was sixty and at the time of his discharge from the service was perfectly fit. He remained well-until two months before admission to hospital, when he had a severe attack of retrosternal pain extending down the left arm. The pain lasted twenty-four hours. Almost every night afterwards until his admission to hospital he experienced intense shortness of breath, so severe that he had to sit up in a chair for about an hour before being able to return to bed. These attacks occurred in spite of the use of several pillows.On admission he was orthopnceic and dyspnceic at rest. The neck veins were distended and pulsating and there was slight sacral aedema. The pulse was regular and the blood pressure 120/80. The heart was not enlarged. There was a systolic thrill to the left of the lower end of the sternum, and a systolic murmur, loud in all areas but maximal at the inner end of the fourth left intercostal space. There were no abnormal signs in the lungs apart from scattered rhonchi and basal crepitations. Slight hepatic enlargement and tenderness were the only abnormal findings on abdominal examination. The venous pressure was 150 mm. of water. A radiogram of the chest showed slight left ventricular enlargement and some pulmonary congestion. A cardiogram showed sinus rhythm. The significant abnormalities were found in the unipolar prncordial leads.Whereas R in VI was 1 mm. high, R in V2 was only 0-5 mm. high and in V3 was even less. A small Q was present in leads V4 to V6. The S-T segments were elevated in all these leads.A diagnosis was made of anteroseptal myocardial infaction with rupture of the interventricular septum and congestive cardiac failure. After treatment for one month with rest in bed, digitalis, and mercurial diuretics he was allowed to go home. He remained well for two weeks and then began again to experience attacks of cardiac asthma. Four weeks after his discharge he was admitted to hospital again with symptom...