CELL STRUCTURE AND FUNCTION

AMONG the many cardiovascular anomalies which modern techniques of investigation and treatment have brought into sharper focus, the anomalous origin of the left coronary artery from the pulmonary artery presents an intriguing story. This abnormality generally results in death in early infancy, but in a proportion of cases an extensive collateral circulation develops between the normal right and the abnormal left coronary arteries, and the patient may survive for years, even into adult life. It was formerly thought that the cardiac embarrassment in such cases was primarily due to the perfusion of the left heart muscle with venous blood from the pulmonary artery, and it has only recently been realized that this is not so. The collateral channels between right and left coronary arteries result in a reversed flow down the left artery into the pulmonary artery; the system acts as an arterio-venous fistula, and the relative anoxia of the heart muscle is due to the low pressure in the coronary arteries, especially on the left side. The treatment therefore is to ligate the anomalous artery at its junction with the pulmonary artery.