title: Prevalence of retrograde conduction in heart block after DDD pacemaker implantation.
abstract: Electrophysiologic studies were performed before DDD pacemaker implantation in 50 patients with symptomatic heart block. The patients were separated into 2 groups. Group I consisted of patients with intact retrograde conduction and group II consisted of patients with blocked retrograde conduction. After pacemaker implantation, postventricular atrial refractory periods in patients in group I were programmed at 50 to 100 ms, in excess of the retrograde conduction times measured during electrophysiologic studies. In group II patients, postventricular atrial refractory periods were routinely programmed at 300 ms. During follow-up, patients visited the outpatient clinic at 3-month intervals for noninvasive assessment of the prevalence of retrograde conduction, and to test the inducibility of pacemaker-mediated tachycardias. The mean follow-up of group I (15 patients) was 27 +/- 10 months, whereas the mean follow-up of group II (35 patients) was 19 +/- 9 months. The mean number of noninvasive tests performed during follow-up was 8 +/- 3 per patient for group I and 5 +/- 3 per patient for group II. In group I, retrograde conduction remained intact in 12 patients (p less than 0.01). In 29 of 31 patients in group II, retrograde conduction remained absent (p less than 0.01). In 4 patients in group II, chronic atrial fibrillation occurred during follow-up. Chronic atrial fibrillation did not occur in any patient in group I. During serial electrophysiologic testing, no pacemaker-mediated tachycardias could be induced in any patient in group I or II.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D004553:Electric Conductivity; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000503:physiopathology* / Q000628:therapy; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D013686:Telemetry
chemical_list: D000889:Anti-Arrhythmia Agents