Dynamic electrophysiological examination of heart in patients with sick sinus syndrome in continuous pacing

Objective: Dynamic electrophysiological examination of the heart with allowances for ECG variants of this syndrome and stimulation regimen was performed to predict the results of continuous pacing in patients operated for sick sinus syndrome (SSS).

Methods: 32 patients had the diagnosis of bradycardia SSS (group 1), 15 patients--bradytachycardia (group 2). 30 patients were on ventricular VVI stimulation, 17 patients--on atrial AAI stimulation. Electrophysiological examination of the heart was performed by means of transesophageal left atrial pacing under programmed, frequent and ultrafrequent stimulation 1, 2, 3 and 4 years after the start of continuous cardiac pacing.

Results: In group 2 depression of the sinus function (corrected time of the sinus function recovery, frequency of spontaneous pacemaker, duration of poststimulation pause) under pacing was more distinct than in group 1. Deterioration of atrioventricular conduction was greater in group 1. Three and four years after pacing the Wenckebach point in group 1 lay significantly lower than in group 2. Within the follow-up period 6 (12.8%) patients developed AB-block of the second degree. 4 patients of them were from group 1. Arrhythmogenic atrial readiness depended on the kind of cardiac affection more than on stimulation regimen.

Conclusions: Dynamic electrophysiological cardiac examination in the presence of pacing allows following up of natural course of sick sinus syndrome and early correction of the stimulation regimen.