Key result
Reprogrammed rate-adaptive pacing closely mirrors spontaneous heart rate and tracks metabolic workload during exercise.
Why the study?
The proportionality of pacemaker rate response to metabolic workload and the effect of reprogramming rate response parameters to match sinus rate were not previously demonstrated.
Does reprogramming rate response parameters in a rate adaptive pacemaker improve the proportionality of the sensor indicated rate to metabolic workload compared to spontaneous sinus rate in patients with sick sinus syndrome or AV block?
Does reprogramming rate response parameters in a rate adaptive pacemaker improve the proportionality of the sensor indicated rate to metabolic workload compared to spontaneous sinus rate in patients with sick sinus syndrome or AV block?
Reprogramming rate response parameters in rate adaptive pacemakers can produce a sensor-indicated rate that closely mimics the physiological sinus rate during varying metabolic workloads.
PM rate response may drift over 2 years post-implant; leaves open whether periodic reprogramming improves exercise tolerance in sick sinus syndrome.
OBJECTIVE: The rate response of a pacemaker (PM) was compared with the sinus rate in patients during repeated exercise tests, at different settings of the rate response parameters. METHODS AND RESULTS: In patients with paroxysmal sick sinus syndrome (n=3) or atrioventricular block (n=8), a rate responsive PM was implanted. The activity-dependent pacing rate is represented by the sensor indicated rate (SIR). Each patient performed a treadmill test at 1 month, 1 year, and 2 years after implantation. Prior to the 1 and 2 year tests PM parameters were changed to produce a larger rate increase, especially at moderate levels of daily life activity. During the tests the O(2) consumption and CO(2) production were measured, breath-by-breath, to determine the workload and the anaerobic threshold. On average the workload (oxygen consumption), the patient's sinus rate, and the SIR, showed a linear increase with the workload imposed by the treadmill. In the 1 month and 1 year test the SIR was much lower than the spontaneous rhythm, especially at low or moderate workloads. On the more dynamic setting of several rate adaptive parameters at 2 years, the SIR changed significantly and was close to the spontaneous HR. CONCLUSIONS: The examined PM provides a paced heart rate that is proportional to the workload. For the first time the effect of reprogramming rate response parameters to produce an SIR that is similar to the sinus rate is shown in this study.
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Schuster et al. (2005) studied Paroxysmal sick sinus syndrome or atrioventricular block (n=11). Reprogramming of rate response parameters in a rate adaptive pacemaker vs. Spontaneous sinus rhythm / baseline settings was evaluated on Sensor indicated rate (SIR) compared to spontaneous sinus rate and metabolic workload during exercise. Reprogramming rate response parameters of a rate adaptive pacemaker produced a sensor indicated rate that was proportional to metabolic workload and closely matched the spontaneous heart rate.
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