Heart rate and arterial blood pressure during exercise in patients with angina pectoris. Effects of training and of nitroglycerin.

In 29 patients with typical exertional angina pectoris, intra-arterial systolic blood pressure (SBP), heart rate (HR), and the rate-pressure product (RPP = HR X SBP X 10(-2) were continuously recorded during repeated bouts of leg or arm exercise. Development of chest pain was independent of the workload and occurred at a fairly constant value of RPP, of HR, and of SBP in each patient for a given type of exercise, but the pain threshold values for all three variables were consistently higher during arm exercise than during leg exercise. The reproducibility of the pain threshold values was assessed for leg exercise. The variation, based on individual coefficients of variation, ranged from 1.3% to 13% (group mean, about 6%). There was no significant difference between the SBP values obtained by the traditional, noninvasive cuff technique and the values during intra-arterial monitoring. In 25 patients a physical training program of an average of three months increased the maximal amount of work (watt X sec) performed before onset of pain by 100%. The most conspicuous effect of training on cardiac function was a 10% reduction of HR at a given workload, SBP being unchanged. Over-all, the data suggest that the increased exercise capacity caused by training could be accounted for by the reduction in the relation between RPP and external workload. The improvement in exercise capacity resulting from training was on the same level of magnitude as the 90% increase obtained in 11 untrained patients after administration of 0.25 to 0.50 mg of nitroglycerine sublingually prior to exercise. In contrast to the finding after training, nitroglycerin administered to subjects increased HR by 10%, but reduced SBP by 13%, RPP remaining unchanged. Therefore to explain the effect of nitroglycerin on exercise capacity additional economizing changes in myocardial performance (e.g., reduction of heart volume) are required.