Usefulness of Rate Responsive Atrial Pacing in Patients with Sick Sinus Syndrome

Abstract

We studied heart rate response and blood lactate changes during treadmill exercise testing in 10 patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction in whom an activity detecting multi‐programmable rate responsive pacemaker was implanted for atrial pacing (AAI pacing). Treadmill exercise testing was performed twice in each patient under the two different AAI pacing modes: rate responsive function off (fixed rate 60 pulses per minute [ppm]; RR‐off) and rate responsive function on (rate response 10, activity threshold medium, basic rate 60 ppm, and maximum rate 150 ppm; RR‐on). Chronotropic response and blood lactate change during exercise were compared among patients under each pacing mode and eight healthy volunteers of ages matching those of the patients. In patients under the RR‐off pacing mode (RR‐off patients), chronotropic response was lower (P < 0.01) and blood lactate level was higher (P < 0.05) than those in patients under the RR‐on pacing mode (RR‐on patients) and volunteers during exercise. In RR‐on patients, however, both chronotropic response and lactate level changes during exercise were comparatively improved, with no significant differences between RR‐on patients and volunteers. These data suggested that improvement of chronotropic response by rate responsive pacing, in comparison with nonrate responsive pacing, increased the blood supply to the working muscles and resulted in less lactate production during exercise. It was concluded that rate responsive AAI pacing which could maintain AV synchrony and normal intraventricular conduction was an optimal physiological pacing mode for SSS patients with normal AV conduction.

Long-Term Outcome of Single-Chamber Atrial Pacing Compared with Dual-Chamber Pacing in Patients with Sinus-Node Dysfunction and Intact Atrioventricular Node Conduction

“…A previous report showed that dual-chamber pacing may also prevent the progression to AF by overdriving the atria, which is somewhat effective in suppressing atrial ectopic activity and AF 10. However, Nielsen, et al showed that a long-term dual-chamber pacing induces left atrial dilation by right ventricular (RV) pacing, subsequently promoting AF, and Kristensen, et al demonstrated that single atrial chamber pacing was associated with significantly less AF in patients with SSS and normal AV conduction 11.…”

Which Pacemaker?

“…These patients also tend to exhibit more severe peripheral and coronary arterial disease 14 . Recent evidence suggests, however, that atrial pacing in AAI and AAIR modes reduces morbidity and mortality by decreasing the incidence of atrial fibrillation and peripheral embolisation as well as improving congestive cardiac failure compared to ventricular pacing 15 , 16 …”

“…These modes utilise the normal conduction system and are the most ‘physiological’ presently available 29 . Atrial pacing also improves long‐term survival and tends to decrease the incidence of paroxysmal atrial tachyarrhythmias compared to ventricular pacing modes 15 , 16 . Clearly, AV nodal conduction must be closely assessed and proven to be normal prior to, or during, the implantation procedure.…”

“…29 Atrial pacing also improves long-term surviv.al and tends to dec.rease the incidence of paroxysmal atnal ｴ ｡ ｣ ｾ ｡ ｲ ｲ ｨ ｹ ｴ ｨ ｭ ｬ ｡ ｳ compared to ventricular pacing modes. I , 16 Clearly, AVnodal conduction must be closely…”

Atrial adaptive rate pacing in sick sinus syndrome: effects on exercise capacity and arrhythmias.

“…Thirteen male and 17 female patients, mean (SD) age 65 (12) years, satisfied the inclusion and exclusion criteria and were admitted for implantation of programmable AAIR systems. '5 Medtronic Activitrax II and Telectronic Meta MV generators with their recommended atrial leads, were implanted alternately.…”