Rupture of the interventricular septum occurring as a complication of myocardial infarction has been reported with increasing frequency. The condition, at one time thought to be rare, is not uncommon and is of prognostic importance. It is, however, less common than rupture of the ventricular wall, for in a series of 698 cases ofcoronary occlusion, 6 per cent suffered from this latter complication (Bean, 1938). Prior to 1940 there were isolated reports of single cases, though Sager (1934) collected eighteen that had been reported, and Weber (1943) made a further review. Including the seven described here it is possible now to find reference to 113 cases.Five of the cases of septal perforation described in this paper were diagnosed during life; one at necropsy, the correct diagnosis not having been made in life; and one was the subject of a coroner's post mortem, the patient being found dead. During the last seven years in which records are available in this hospital group, 219 men and 99 women have been seen with cardiographic evidence of salient cardiac infarction using standard criteria (Evans, 1954). Case 1. An obese woman, aged 53, experienced the pain of myocardial infarction, severe enough to cause vomiting and sweating. She had had two years previously a left hemiparesis but had made a good recovery: she had been dyspnceic on effort for some years but had never had anginal pain on effort nor any history of a previous coronary occlusion. Her father had died of a cerebral vascular accident at the age of sixty eight.She was seen by her own practitioner that evening who thought that she had had a myocardial infarction, and at that time she had no murmur. When seen the following morning she was cyanosed, her blood pressure was 80/70 mm. Hg, her apex beat five inches from the mid line in the fifth space, and over the whole of the praecordium there was a loud rough pansystolic murmur accompanied by a thrill; coarse crepitations were heard at the bases. She was admitted to hospital, and anticoagulant therapy commenced. With 1-noradrenaline her blood pressure rose to 90/80 mm. Hg, but her condition deteriorated, venous congestion appeared, and she died three days after the onset of pain. Her cardiogram (Fig. 1), showed an extensive anterior myocardial infarction with prominent S-T plateaux in leads VI to V4.Necropsy revealed a small amount of blood-stained pericardial fluid. The heart weighed 450 g., the left ventricle was large, and there was a recent infarct involving the apex and anterior wall of the left ventricle, the lower part of the interventricular septum was involved, and this had ruptured in its lower part. There was severe atheroma of the aorta and all the coronary vessels, and a recent thrombus was present in the descending branch of the left coronary artery. She had bilateral pulmonary cedema and a congested liver which weighed 1500 g.
