THE DIAGNOSIS of coronary artery disease in the presence of a normal resting electrocardiogram has been aided by the use of tests designed to create a relative hypoxemia of the myocardium, the best known of which are the Master two-step test1 and the anoxemia test of Levy.2 The former method relies upon a standardized amount of exercise based on age, weight, and sex to create a greater demand for oxygen by the myocardium, whereas the anoxemia test decreases the amount of oxygen to the heart through the inhalation of a 10% oxygen mixture for a 20-minute period. The electrocardiographic changes which occur with these procedures in the presence of coronary disease are reflected mainly by RS-T segment depressions and/or T wave inversions in one or several leads. These alterations are similar in both tests and are thought to be due to factors common to the effects of exercise
TEWELL HE, PRITCHARD JS. CONTROLLED HYPOXEMIA TEST FOR CORONARY INSUFFICIENCY EMPLOYING THE MILLIKAN OXIMETERA Study of Normal and Abnormal Responses. AMA Arch Intern Med. 1952;90(4):435–443. doi:10.1001/archinte.1952.00240100012002
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