Incidence and Timing of Activity Parameter Changes in Activity Responsive Pacing Systems

Abstract

The incidence and timing of rate response parameter reprogramming in activity responsive pacing systems during the year after implantation was evaluated in two groups of patients: 24 patients in whom a VVI,R system was implanted (Activitrax, Medtronic, Inc.), and 21 patients in whom a DDD,R system was implanted (Synchrony, Siemens Pacesetter, Inc.). Activity parameter changes in Activitrax patients were made based on the presence of symptoms, while in Synchrony patients, changes were based on objective data obtained using a sensor indicated rate histogram with a slow and fast walk protocol. No significant difference in the incidence of activity parameter reprogramming was noted at various time intervals during the first year in Activitrax patients; in Synchrony patients a greater incidence of reprogramming changes was noted at the 1-month follow-up visit compared to later follow-up visits (P less than 0.02). Further, the incidence of changes at 1 month was greater for Synchrony compared to Activitrax patients (P less than 0.001), while no difference was detected between groups at subsequent follow-up intervals. Use of the slow and fast walk protocol, by permitting serial evaluation of sensor response, demonstrated alterations in sensor drive rates with similar levels of activity over the initial 4 to 6 postimplant weeks. This may result from postoperative changes at the pacemaker insertion site. Based on this experience, predischarge programming may not predict long-term rate response requirements. We recommend evaluation of sensor function using an exercise protocol performed at 4 to 6 postimplant weeks in all rate responsive pacing systems that utilize a piezoelectric crystal.

Application of an accelerometer in adjusting parameters and detecting characteristics in the pacemaker rate response

“…The placement direction of the accelerometer's three-axes (Axis-1, Axis-2 and Axis-3, respectively) was basically parallel as the direction of the participant's anatomical reference axis [vertical axis (Y-Axis), coronal axis (X-Axis) and sagittal axis (Z-Axis), respectively]. Then, by following the PM programming manual and the modified exercise test method in the literature (Ahern et al 1992), the first walking test was performed for approximately 4 min, and the participants walked in the corridor of the ward, with a length of 20 metres. The step pace was as uniform as possible, without stopping halfway, and the step pace was determined by the participants.…”

“…They needed to adapt to this exercise mode, and some elderly and weak patients could not cooperate to complete the test. Because the walking test method is simple and the gait is natural, it has become a common clinical exercise protocol (Ahern et al 1992, Coenen et al 2008, Shaber et al 2008. However, during the walking test, estimating activity intensity only on the basis of step pace has certain limitations in accuracy and objectivity, so the setting of the SIR is subjective and empirical.…”

“…c P<0.05, comparison with the other two PM types. NN50: the number of cardiac cycles with a time interval difference50 ms between adjacent cardiac cycles (that is the NN interval).DiscussionAt present, in the activity-sensing rate response PMs, there are mainly two methods to use for adjusting pacing rate (and the SIR) on the basis of activity intensity, which include both automatic adjustment of rate response parameters, and during exercise test, manual setting of rate response parameters(Ahern et al 1992, Erol-Yilmaz et al 2005, Schuster et al 2005…”