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

Objective. To study the application of an accelerometer in adjusting the parameters, setting the sensor indicated rate (SIR) and detecting characteristics in the pacemaker (PM) rate response. Approach. Three-axis (GT9X Link-type) accelerometers were positioned on the waist and chest in 33 participants implanted with rate responsive PMs while wearing an ambulatory ECG recorder (Holter). During the walking test, by collecting vertical axis (Axis-1) activity intensity counts, Axis-1' metabolic equivalent of energy (METaxis-1) and its expected heart rate (HRmet-axis1) were calculated by the relevant equations, and on the basis of the HRmet-axis1 as the target heart rate, the SIR was set by programming the rate response slope parameter. During the following daily walking activity, the physical activity parameters and Holter ECG was recorded continuously. After the end of the whole test the analysis on these data recorded was performed retrospectively. Main results. After completing the SIR setting, in 24 participants with complete ventricular pacing the comparison between HRmet-axis1 (92.5 +/- 7.8 BPM) and the HRvp-Holter (94.0 +/- 10.5 BPM) showed no statistical difference (Delta HR: 1.25 +/- 6.69 BPM, P: 0.568) during the last one walking test, and there was also no significant difference (Delta HR: 2.8 +/- 7.1 BPM, P: 0.398) between the HRmet-axis1 (90.7 +/- 7.1 BPM) and HRvp-Holter (93.4 +/- 10.3 BPM) during daily walking activity. In addition, in the data of 108 time intervals selected during the daily walking activities in the abovementioned 24 participants, METaxis-1 and HRvp-Holter correlation analysis showed good correlation and the regression equation was HR = 12.4 x MET +/- 43.1 (P < 0.0001). Significance. An accelerometer can play an important role in adjusting parameters, setting the SIR and detecting characteristics in the PM rate response.