Relation between metabolic acidosis and cardiac dysrhythmias in acute myocardial infarction.

In the past 30 years mortality in acute myocardial infarction had remained virtually unchanged, varying between 30 and 40 per cent. Recently, with the advent of the coronary care unit, it has become possible to increase the patient's chance of survival, partly by the more energetic treatment of cardiogenic shock, but largely by the prompt suppression of the minor dysrhythmias which are such a common feature of the early phase of acute myocardial infarctions. These lesser dysrhythmias, as well as reducing circulatory efficiency, may herald the graver disturbances of rhythm such as ventricular tachycardia and ventricular fibrillation, and their prevention would, therefore, be an important factor in improving the prognosis in this disease. Experimental and clinical experience suggest that extreme metabolic acidosis may be a factor in producing dysrhythmias, even where respiratory compensation has resulted in a normal arterial pH. Metabolic acidosis is known to occur in the early stages of an acute myocardial infarction (Mackenzie et al., 1964; Neaverson, 1966; Kirby and McNicol, 1966), but it is rarely severe except in the presence of profound cardiogenic shock; nevertheless, it could contribute to the development of dysrhythmias.