Some Clinical Aspects of Coronary Occlusion

THE terms "coronary occlusion," "coronary thrombosis," and "cardiac infarction" are often indiscriminately employed as if these expressions were terms synonymous. This is in fact not the case, and differences are well marked between them. Cardiac infarction is the result of the coronary occlusion, and represents the pathological change which has occurred in the myocardium as a result of the arterial block, and may take some hours or even days to develop. It may also be completely absent if the patient should die, after the acute occlusion, before time is allowed for these changes in the muscle to take place. Coronary thrombosis is often used to denote coronary occlusion, although it is only a special type of it. It presupposes a knowledge of the cause of the occlusion, which from clinical examination it is impossible to have, and which may even be refuted by future pathofogical examination. Thus, although coronary thrombosis is the commonest cause of the final occlusion, it is by no means the only cause. It is therefore safer to employ the non-specific term, coronary occlusion, for the clinical concept. The clinical importance of coronary occlusion cannot be overstressed. It is a condition which causes death and much disability in middle age and late adult life, and, as it usually afflicts those of a dynamic, forceful personality, its economic importance is great. It also is a disease of great personal importance to medical men, for it ranks highest as a cause of death in medical men in America and possibly also in this country. There is an opinion also, abroad, that the incidence of the disease is increasing. Although statistical evidence fails to confirm this, it suggests that this increase is more apparent than real, and is due to better diagnosis, the more full investigation of cases of acute thoracic pain, and the recognition of minor coronary episodes and their differentiation from so-called "acute indigestion." The facts which have been utilised are derived from a personal survey of the case records of 121 cases of coronary occlusion admitted to the Royal Victoria Hospital over a twelve-year period, and all factors were critically analysed. No attempt to discuss oetiology or prognosis will be attempted, but only a presentation made of some aspects of the clinical picture. Apart from the rare accident of coronary embolism, coronary occlusion seldom occurs except in a heart with diseased coronary vessels, and the predisposing disease of greatest importance is coronary atherosclerosis. Coronary occlusion, therefore, is a condition superimposed on coronary atherosclero'sis, and can be considered under two, or at most, three stages in its clinical development 1. The stage of coronary atherosclerosis. 2. The pre-occlusive state. 3. The acute coronary occlusion.