Ischemic response to sudden strenuous exercise in healthy men

Abstract

In 10 healthy, asymptomatic men, intraarterial pressure and electrocardiograms were recorded during various types of exercise. Potential subendocardial blood flow was estimated from a diastolic pressure time index (DPTI) and myocardial oxygen requirements estimated from the tension time index (TTI). The ratio DPTI/TTI provided an estimate of the supply/demand relationship. With sudden vigorous exercise decrease warmup, the DPTI/TTI was below 0.35 in 3 men who had ischemic electrocardiograms, below 0.44 in 3 men with minor ST abnormalities, and above 0.44 in 4 men with normal ST segments. With a prior warmup exercise, sudden exercise caused no ischemic changes, but DPTI/TTI was below 0.44 in 2 subjects who had minor ST abnormalities. Maximum treadmill testing produced higher heart rates and TTI than did sudden exercise, but DPTI/TTI was above 0.44 in all cases and no ST abnormalities occurred. Abnormal electrocardiographic responses produced by sudden, vigorous exercise in normal men may represent subendocardial ischemia caused by a transient, unfavorable alteration in the subendocardial oxygen supply/demand relationship which is predictable from arterial pressure measurements.