Paroxysmal Atrial Fibrillation and High Degree AV Block: Use of Single‐Lead VDDR Pacing with Mode Switching

Abstract

Dual chamber rate responsive pacing incorporating a mode switching option is increasingly used in patients with chronic paroxysmal atrial fibrillation and high degree AV block. Single-lead VDDR pacemakers have rarely used for this indication. The purpose of this study was to determine their reliability of atrial sensing during atrial fibrillation, the percentage of atrial synchronous ventricular pacing, and the behavior of the sinus rate outside the phases of atrial fibrillation. We studied ten patients with a single-lead VDDR pacemaker implanted for this indication. Follow-up visits were performed at predischarge and after 1, 3, 6, 12, 18, and 24 months. During the mean follow-up period of 18.9 +/- 6.9 months, the atrial sensing thresholds in sinus rhythm remained stable. Atrial synchronous ventricular stimulation was achieved in 68.7 +/- 31.2% (median 82.5%) of the whole follow-up time. All patients showed an adequate atrial rate response during sinus rhythm. Atrial fibrillation was detected by the pacemakers in 24.0 +/- 29.8% of time. In 3 of 10 patients the duration of atrial fibrillation showed a steady increase from visit to visit. The sensed amplitudes of atrial fibrillation ranged from 0.1-1.0 mV. A programmed atrial sensitivity of 0.1 mV was necessary to achieve complete sensing of atrial fibrillation. None of the patients experienced tachycardias with optimized pacemaker programming. Single-lead VDDR pacing incorporating a mode-switching option is useful in patients with high degree AV block and paroxysmal atrial fibrillation, since it provides atrial synchronous ventricular pacing in more than two-thirds of follow-up time. In a subgroup of patients, a progressive increase of the time during atrial fibrillation was demonstrated. A reliable detection of paroxysmal atrial fibrillation requires the programming of the atrial sensitivity to its most sensitive value.

Analysis of Mode Switching Algorithms in Dual Chamber Pacemakers

“…26 This is crucial in VDD systems which should always switch from nonrate responsive tracking mode to rate responsive nontracking mode. 57 The clinical impact of the delay before the device returns to tracking mode upon ATA cessation has never been investigated separately in a clinical study. However, if there is a desire for AV synchrony during sinus rhythm, return to tracking mode should be as fast as possible.…”

Pacemaker Diagnostics:

“…For example, P wave histograms have been used to display multiple measurements of the P wave amplitude during the follow‐up (Table III). The ability of the histogram to display multiple measurements has been shown to facilitate the optimization of the programmed atrial sensitivity 16–19 . Fluctuations may be detected that would not have been apparent if thresholds are evaluated only at pacemaker interrogation.…”

“…6). 16 Stored histograms are also used to obtain a graphic display of the range of atrial and ventricular rates that have occurred during follow‐up (Table I). The percentage of the total number of sensed and paced complexes occurring at each rate can be displayed as various bar graphs (Fig.…”

Impact of high‐grade atrioventricular block and cumulative frequent pacing on atrial arrhythmias

“…1,3,4 AF is associated with multiple comorbidities including conduction abnormalities and pacing modalities. [5][6][7] Frequent right ventricular (RV) pacing (RVP) has been associated with increased rates of AF in patients with sinus node dysfunction (SND); however, the same association has not been consistently demonstrated in patients with high-grade atrioventricular block (HGAVB) treated with dual-chamber pacemaker (DC-PPM) implantation. [8][9][10][11] The relationship between HGAVB with cumulative frequent RVP and the risk of AAs requires further characterization to help guide clinical management.…”

“…Atrial fibrillation (AF) is particularly prevalent among individuals over age 65 in the United States, affecting 9% of this pospulation . AF is associated with multiple comorbidities including conduction abnormalities and pacing modalities . Frequent right ventricular (RV) pacing (RVP) has been associated with increased rates of AF in patients with sinus node dysfunction (SND); however, the same association has not been consistently demonstrated in patients with high‐grade atrioventricular block (HGAVB) treated with dual‐chamber pacemaker (DC‐PPM) implantation .…”