Pacing studies after cardiac surgery.

The diagnostical use of pacemaker after cardiac surgery is presented. Temporary pacemaker electrodes have been inserted during surgery into the wall of atrial and ventricular myocardium. With the aid of these electrodes, an analysator wire of 6 volts, and a Medtronic 5840 type pacemaker electrophysiological studies have been performed. The diastolic and supernormal stimulation threshold, the duration of atrial and ventricular relative refractory period were measured, the clinical significance of latency was analysed. It has been found that decrease of stimulation threshold, shortening of relative refractory period, and appearance of latency phenomenon promote arrhythmias. By investigating the conduction capacity of atrioventricular conduction system, latent conduction disturbances could be revealed, and a significant difference could be demonstrated between the atrioventricular conduction of WPW syndrome and that of other kinds of PR interval shortening. In addition the optimal heart rate requirement (optimal pacing rate) following heart surgery was defined. These parameters present more precise information on the electrophysiological condition of the heart than does the generally used ECG monitoring. When these parameters are repeatedly determined, the significance of patient's arrhythmias can be evaluated more safely and accurately; in a number of cases, even in the absence of any rhythm disturbances, impending arrhythmias can be predicted. "Pacemaker monitoring" of the postoperative heart patients, therefore, affords greater possibility for preventing the development of major cardiac arrhythmias.