Effect of Restoration of AV Synchrony on Stroke Volume, Exercise Capacity, and Quality‐of‐Life: Can We Predict the Beneficial Effect of a Pacemaker Upgrade?

Abstract

The aim of this study was to assess to what extent patients with VVIR pacemakers and without overt symptoms of a pacemaker syndrome benefit from a pacemaker upgrade, and if a preoperative noninvasive measurement of the change in stroke volume (SV) could predict the effect of a pacemaker upgrade. The study group consisted of 20 (12 women, 8 men) VVIR patients with a mean age of 60 years. The indication for the first implantation was AV block in 13 patients and SSS in 7. The mean time of a ventricular pacing was 77 months. The objective (echocardiography, an exercise capacity) and the subjective (the quality-of-life) parameters investigated in patients during ventricular pacing were compared to results obtained 2 months and 1 year after a pacemaker upgrade. To assess preoperatively a change in a SV expected after upgrading, attempts were made to restore AV synchronization by the use of a transesophageal pacemaker. An increase in SV (from 5% to > 35%) during temporary AV resynchronization was observed in each patient. Values of SV increase correlated with those obtained 2 months (r = 0.65; P < 0.01) and 1 year (r = 0.66; P < 0.01) after an upgrade. Superior hemodynamics was associated with a significant improvement of an exercise capacity in both subgroups of patients. The most significant improvement in the quality-of-life was observed in patients with SSS. We did not find correlations between SV and the quality-of-life assessed 2 months (r = 0.043; NS) or 1 year (r = 0.02; NS) after an upgrade. In conclusion, a pacemaker upgrade performed after a long-term ventricular pacing resulted almost consistently in the improvement of hemodynamics and was associated with an increase of exercise capacity. In patients with SSS it was followed by the significant improvement of their quality-of-life. Such a relation was not observed in patients with AV block as some of them (especially those with VVIR pacemakers) felt quite well during ventricular pacing. The proposed preoperative echocardiographic evaluation may precisely predict the degree of hemodynamic improvement expected after a pacemaker upgrade.

High incidence of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based pacing in the Mode Selection Trial (MOST)

“…In one study, 16 patients with VVIR pacemakers were given atrial leads and randomized to ventricular demand pacing or physiologic pacing; perceived well-being and exercise capacity were improved during physiologic pacing (14). This finding was confirmed in 2001 in a similar study of 20 patients who had an atrial lead placed at the time of generator replacement; stroke volume and exercise capacity were increased in all individuals, and those with sick sinus syndrome had an improvement in quality of life (15). Finally, it is also possible that the greater percentage of beats paced (which was predictive of the development of pacemaker syndrome in the current study) was lower in those studies that reported low frequencies of pacemaker syndrome.…”

“…It is possible that subclinical pacemaker syndrome may be present and undiagnosed in studies that require surgical revision to upgrade patients to a physiologic-based system (14,15). In one study, 16 patients with VVIR pacemakers were given atrial leads and randomized to ventricular demand pacing or physiologic pacing; perceived well-being and exercise capacity were improved during physiologic pacing (14).…”

Profound Hypotension Due to Slow Atrioventricular Nodal Pathway Conduction during Atrial Tachycardia

“…Due to the prolonged AV delay during slow pathway conduction of atrial tachycardia, each atrial contraction was likely simultaneous with the preceding ventricular systole. Contraction of the atrium against closed AV valves may lead to reduced cardiac output due to loss of atrial contribution to ventricular filling, and to baroreflex‐mediated autonomic changes 7–10 …”

The role of cardiopulmonary exercise testing in the initial evaluation of patients wearing intracardiac devices submitted to cardiac rehabilitation

“…To prevent these malfunctions, the devices of the patients submitted to physical rehabilitation have to be reprogrammed accordingly after establishing their maximum heart rate during the exercise test [18,19]. Several clinical studies have shown that the programming mode of the cardiac pacemakers can also have a significant influence on the patients exercise capacity, a crucial element of any physical rehabilitation program (table 3) [20,21,22]. The most frequently implanted pacemakers are singlechamber (VVI -right ventricular pacing) and dualchamber (DDD -right atrial and right ventricular pacing), with or without the rate response function activated.…”