A study on the rehabilitation of ischemic heart disease patients. The heart rate, beta-receptor blocking agents and strength-duration relationship of exercise.

Exercise tests with bicycle ergometer were performed in 9 normals and 54 patients with ischemic heart disease (IHD), in order to evaluate the heart rate (HR) as a parameter for determining the physical working capacity and controlling the daily activities, and to observe the circulatory and metabolic effects of beta-blockers and moreover to study the strength-duration relationship of exertion. The following results were obtained and discussed: 1. Reliable correlation between heart rate and O2 consumption during all phases of exercise, including the recovery period (R = 0.60-0.87, p less than 0.001) and parallelism of heart rate and pressure rate product allows the heart rate to be used as a parameter for myocardial O2 demand and ST-T changes. It is reasonable to evaluate the exercise effect by the net increment of heart rate during and after exercise, and to utilize the increment of heart rate in the recovery period for the evaluation of physical fitness and adaptability. 2. Similar to other studies made on beta-blockers, in this study too, the agents including Kö 1366 suppressed the exercise responses of heart rate (p less than 0.01), the product of heart rate and blood pressure (p less than 0.01), and O2 consumption (p less than 0.01). But a relatively slow recovery of O2 consumption from the peak response towards pre-exercise level and a higher O2 pulse in the early recovery period was observed after beta-blocker medication. 3. Capillary (ear lobe) pH decreased and recovered in correlation with the strength of exertion. This corresponded with the response of other factors such as ST-T, heart rate, pressure-rate product, and O2 consumption, showing that the exercise strength was one of the more dominant factors to determine allowable work load for ischemic heart disease patients. 4. Recovery of pH was delayed after medication with Kö 1366 (p less than 0.01).