THE FLOW OF BLOOD IN THE CORONARY ARTERIES IN PATHOLOGICAL HEARTS

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Abstract
In hearts of patients who have died of heart failure, the coronary blood flow was diminished either absolutely, as in the disease of coronary arteries and in dilatation of the heart, or relatively, as in hypertrophy. Under the conditions of these expts., it appeared that any rate of flow less than .75 cc. per g. of heart muscle per min., endangered the function of the heart. Hypertrophy or dilatation both reduced the coronary flow per g. of heart muscle. In hypertrophy an increase in muscle mass caused a relative reduction in dilatation. Lengthening and stretching of the coronary vessels caused the chief reduction. In dilatation it is suggested that lengthening and stretching of coronary vessels was the cause of increased flow. In these hearts the coronary flow was increased during systole and decreased during diastole; a result directly opposite to that found in hearts with normal diastolic volume. In the dilated heart, drugs which tended to decrease the diastolic volume increased the coronary flow, while those which augmented the diastolic volume diminished the flow. Again the reaction is directly opposite to that in undilated hearts. This finding suggested that the physical state of the heart, particujarly the degree of dilatation, must be considered in the selection of drugs for the treatment of cardiac disease.