Noninvasive evaluation of cardiac function in patients with ischemic heart disease by the subclavian arterial blood flow response to exercise

Abstract

To evaluate cardiac function, the regional blood flow of the subclavian artery as a parameter of cardiac output was measured instead of measuring cardiac output itself in 12 normal subjects and 17 patients with ischemic heart disease. The measurement of the subclavian arterial blood flow was continuously and noninvasively made utilizing the Doppler ultrasonic flow-meter before, during and after exercise. The exercise was performed in the upright position on a bicycle ergometer for 3 minutes at the work load of 230 Kpm/min. ΔF Ratio, that is, the ratio of the increased blood flow during the exercise to the increased blood flow during the first 3 minutes after the termination of the exercise, was calculated in all subjects. ΔF Ratio as well as the response pattern of the blood flow to exercise was investigated. In patients with ischemic heart disease, the increase in the subclavian arterial blood flow during the exercise was slow, and the time required to return to the pre-exercise level was remarkably prolonged in comparison with normal subjects. The mean ΔF Ratio of the younger normal group was 7.43, and that of the older normal group was 5.53. While in patients with ischemic heart disease, markedly lower values were observed. The mean ΔF Ratio of the following subgroups of patients with ischemic heart disease, the myocardial infarction group, the angina pectoris group, and the group of ischemic heart disease without pain, were 1.25, 1.97, and 2.52 respectively. The difference in the mean ΔF Ratio between the older normal group and each subgroup of ischemic heart disease was statistically significant. Low ΔF Ratio in patients with ischemic heart disease is supposed to be the manifestation of diminished cardiac reserve due to decreased myocardial contractility. As a simple parameter of cardiac output, the contiuous measurement of the subclavian arterial blood flow by the Doppler flowmeter is a useful method for the noninvasive evaluation of cardiac function. Especially, the calculation of ΔF Ratio may provide the numerical presentation of cardiac function. © 1975, The Japanese Circulation Society. All rights reserved.