A noninvasive study of the response of ischemic heart to exercise

The response to exercise during increasing workloads (supine bicycling), was studied in 105 men, of whom 70 had ischemic heart disease and 35 did not, clinically classed into 6 groups. Heart rates, blood pressures and systolic time intervals (STI) were measured in relation to exercise tolerance and capacity. The ischemic heart disease (IHD) subjects differed from the nonischemic by an increased PEP/LVET ratio at rest and by a tendency of the diastolic blood pressure to increase upon exercise. Two main types of abnormal reaction of STI to workload were ascertained: (1) prolonged LVETc with respect to controls (prevailing in angina pectoris), and (2) prolonged PEPEc together with shorter LVETc (typical for left ventricular failure). The dominant feature appears to be the depressed contractility in the latter and a decreased compliance (or rate of relaxation) in the former. Estimation of STI may contribute to the evaluation of the exercise tolerance test in long-term examination of ischemic patients.