Response of Oxygen Uptake to Exercise in Coronary Artery Disease

¹ State University of New York Upstate Medical Center, Syracuse, N.Y.

Oxygen uptake one minute after starting to walk on a treadmill with fixed settings of speed and grade (VO₂-1) was found in 24 normal men and 5 normal women to be linearly related to the power requirement against gravity (P) in which P = weight x grade x walking speed. From this finding a standardized determination of VO₂-1 at P = 1072 kg-M/min was devised with averaging of the first two acceptable determinations. Twenty-five normal men and 40 men with coronary artery disease (CAD) were studied. Abnormally low VO₂-1 scores were found in 21 of the CAD patients. In seven patients studied with the technique of the single breath cardiac output (CO), correlation existed between VO₂-1 and cardiac output at one minute (CO-1). Low values of VO₂-1 occurred in 12 of 16 patients with elevated values of left ventricular enddiastolic pressure (p < .05). There was no correlation between VO₂-1 and the number of vessels involved. Data suggest that impaired ventricular performance results in a delayed rise of VO₂. The latter can be observed in about 50 percent of patients undergoing coronary angiography.