[Chronotropic reserve of the heart in stenocardia]

The rate of cardiac contractions was studied prior to and during the bicycle ergometry test and in the period of restitution in 140 patients with angina pectoris of various severity as compared to practically healthy males. In distinction to healthy individuals, patients with angina pectoris reacted to physical exertion of equal force by a higher rate of cardiac rhythm which returned back to normal more slowly in the period of restitution. They were also marked by more rapid "uneconomical" expenditure of the cardiac chronotropic reserves. In angina pectoris, the capacity of the heart to maximum increase in the rate of contractions was limited. With the growth in the severity of chronic coronary insufficiency, the attack of angina induced by muscular exertion developed at a lesser frequency of the cardiac rhythm (p is less than 0.001).