The Output of the Heart in Patients With Abnormal Blood Pressures

Heart failure is preceded by hypertension in a considerable per- centage of cases.O'Hare, Calhoun and Altnow (1) have recently shown that many patients with heart failure of the type called "chronic myocarditis" or "myocardial insufficiency of unknown origin" have had high blood pressure in the past.In any attempt to analyze the effects of high systemic arterial pressure and to evaluate it as a factor in the causation of heart failure, it is desirable to have knowledge of the other dynamic factors known to be concerned in the work of the heart.The work of the heart is determined chiefly by its output of blood per minute, by the pressure in the pulmonary artery and in the aorta against which it pumps, and by the velocity imparted to the blood by the heart.In the absence of greatly increased output the velocity factor is small relative to the other two, although, as Evans (2) has shown, when large outputs are concerned it may be of major importance.Blumgart and Weiss (3) have studied the velocity of blood flow in patients with arterial hypertension.They found that patients with hypertension who exhibited no evidence of circulatory disability could be divided into two groups: in one, the yelocity of blood flow was within the limits of normal, in the other the velocity was retarded.Cardiac output in patients with arterial hypertension has been studied by Plesch (4), by Liljestrand and Stenstrom (5), and by Haya- saka (6).Plesch's results in four cases showed on the average no definite variation in either direction.Liljestrand and Stenstr6m made repeated observations of the cardiac outputs of five women suffering from increased blood pressure and chronic nephritis.They used the nitrous oxide method of Krogh and Lindhard (7) and found 1 !H3