Radionuclide ventriculography for evaluating left ventricular myocardial contractility in patients with implanted pacemaker

: An EKC-500 pacemaker was implanted in 16 patients with coronary heart disease (CHD) and 14 idiopathic conduction disturbance for complete atrioventricular block. After surgery, the patients underwent equilibrium radionuclide ventriculography by using a nuclear stethoscope at rest and during exercise at different stimulation rates with the aim of choosing their optimal values. It was established that patients with idiopathic conduction disturbances showed improved left ventricular contractility at all stimulation rates and their optimal values ranged 60-70 per minute. In patients with CHD, the stimulation rate of 60 impulses/min was optimal at rest, and with this, exercise resulted in a significant deterioration of myocardial contractility, but only the stimulation rate of 80 impulses/min led to a slight improvement, which was due to accessory mechanisms of contractility enhancement. The peak ejection rate was the most sensitive to progressive myocardial dysfunction, yet the basic contractility index was the mean ejection rate.