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Prevalence of retrograde conduction in heart block after DDD pacemaker implantation
Insights
DDD pacemaker implantation effectively prevents pacemaker-mediated tachycardias by managing retrograde conduction. Patients with intact retrograde conduction showed better outcomes, with no induced tachycardias or atrial fibrillation during follow-up.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Symptomatic heart block necessitates pacemaker implantation.
- Understanding retrograde conduction is crucial for optimizing pacemaker function and preventing complications.
Purpose of the Study:
- To evaluate the impact of DDD pacemaker programming on retrograde conduction and pacemaker-mediated tachycardias.
- To compare outcomes in patients with intact versus blocked retrograde conduction.
Main Methods:
- Electrophysiologic studies were conducted before DDD pacemaker implantation in 50 patients.
- Patients were divided into two groups based on retrograde conduction status.
- Postventricular atrial refractory periods were programmed differently for each group, and patients were followed noninvasively.
Main Results:
- In patients with intact retrograde conduction, it remained intact in 12 of 15 patients.
- In patients with blocked retrograde conduction, it remained absent in 29 of 31 patients.
- No pacemaker-mediated tachycardias were induced in either group; however, 4 patients with blocked conduction developed atrial fibrillation.
Conclusions:
- DDD pacemaker implantation with appropriate programming is effective in preventing pacemaker-mediated tachycardias.
- Maintaining intact retrograde conduction appears to be associated with better outcomes, including a lower incidence of atrial fibrillation.
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)