Hemodynamics of the Master Two-Step Test in Hypertension and Healed Myocardial Infarction

ALTHOUGH the two-step exercise test of Master1 has been used extensively to produce electrocardiographic changes of acute coronary artery insufficiency, results of directly measured hemodynamic changes during the recovery period have not been reported. Indirectly measured hemodynamic changes following this two-step test have been reported infrequently since the tables of standardized stress were derived in 1929 from the recovery heart rates and indirect blood pressures in healthy subjects.2 Measurements of the cardiac output by Fick or indicator-dilution principles have not been reported, although the total body oxygen consumption and the energy cost have been determined.5 Hemodynamic data obtained during the change from the upright during exertion to the supine position during recovery might help explain the delay in development of maximal chest pain and of maximal ST-segment changes until the second minute of recovery, as is frequently observed in subjects with coronary artery insufficiency.6 The electrocardiographic two-step test is usually restricted to individuals with normal electrocardiograms but not necessarily to those with normal cardiovascular systems. Therefore, subjects with diastolic hypertension or healed myocardial infarction were studied. None of the subjects had angina pectoris. To determine whether there is a difference in their hemodynamic responses to recovery from exertion a comparison was made between hypertensive subjects with labile diastolic hypertension and those with persistent diastolic hypertension.