[State of intracardiac hemodynamics in patients with sick sinus syndrome during cardiac pacing].

A EKS-500 pacemaker was implanted in 36 patients with the sick sinus syndrome. Out of them, 18 patients had coronary heart disease, 6, hypertensive disease and myocardial hypertrophy, and 12, idiopathic arrhythmias. After surgery, equilibrium radionuclide ventriculography was performed in the patients at rest in the presence of spontaneous rhythm and pacing, as well as during exercise. In patients with idiopathic arrhythmias, cardiac output and index remained within normal ranges during sinus bradycardia, which was attained by increased stroke volume, whereas in patients with myocardial disease, the normal values of these parameters were recorded only at a rate 60 imp/min. During exercise, the patients with idiopathic arrhythmias showed a noticeable rise in cardiac output not only due to higher heart rate, but due to increased stroke volume, and those with myocardial disease displayed the increase only due to higher heart rate.