Impact of Adaptive Rate Pacing Controlled by a Right Ventricular Impedance Sensor on Cardiac Output in Response to Exercise

Abstract

This study examined the effects of adaptive rate pacing controlled by closed-loop right ventricular impedance sensing on exercise hemodynamics. Twelve patients in whom Biotronik INOS2+ pacemakers had been implanted 4-6 weeks earlier participated in the study. All patients completed two graded, symptom-limited exercise tests. The pacemaker was programmed to DDDR with an upper rate limit of 75-85% of the age-predicted maximum heart rate and a lower rate limit of 45-60 ppm. Heart rate was recorded continuously. An average of 5 beats during the last 10 seconds of each exercise stage was used in the analysis. Oxygen uptake (VO2) was measured using open circuit spirometry. The VO2 values from the final 15 seconds of each exercise stage were used for analysis. Stroke volume and cardiac output were measured during the last minute of each stage using impedance cardiography. The test-retest reliability of heart rate and cardiac output responses to graded exercise was assessed using repeated measures analysis of variance, for which the reliability coefficients were r = 0.993 and r = 0.954, respectively (P < 0.01). There were significant correlations (P < 0.01) between VO2 and heart rate and between VO2 and cardiac output, with correlation coefficients of r = 0.907 and r = 0.824, respectively. This method of adaptive rate pacing produced reliable, positive hemodynamic responses to graded exercise on a test-retest basis.

The COGNITION Study Rationale and Design: Influence of Closed Loop Stimulation on Cognitive Performance in Pacemaker Patients

“…But no study investigated if this translates into improved cognitive performance in either short or long term. CLS provides the appropriate and individually tailored heart rate adaptation during physical exercise 8,10,11,16 . Furthermore, it has been reported that CLS is associated with a lower atrial tachyarrhythmia burden than an overdrive pacing algorithm or accelerometer‐based rate adaptive pacing at 7 months after pacemaker implantation 17 .…”

“…While the majority of pacemaker sensors are not able to react on mental stress, closed loop stimulation (CLS) rate‐adaptive systems utilize the natural cardiovascular control loop to obtain a feedback signal that steers the pacing rate 6,7 . CLS devices respond to both mental and physical stress, potentially increasing cerebral perfusion during all kinds of activity 8–12 . Although bearing such potential, there is still no clinical evidence that CLS improves cognitive performance and the overall well‐being of chronotropically incompetent patients in comparison to conventional rate‐adaptive pacing.…”

Closed loop stimulation and accelerometer-based rate adaptation: results of the PROVIDE study

“…Performance of CLS has been evaluated over the years, with favourable clinical results. 12,15,[20][21][22][23][24][25][26][27][28][29][30][31][32] Intraindividual comparisons of CLS with the accelerometer sensor were not available until recently, since no pacing device integrated both sensors. Thus far, three other study groups presented preliminary comparative data, suggesting that CLS is superior to accelerometer-based rate-adaptive pacing regarding acute mental stress, isometric handgrip, deep breathing, Valsalva maneuver, postural change, and quality of life.…”