Clinical Performance of Automatic Closed‐Loop Stimulation Systems

Abstract

Inos pacemakers use contraction dynamics to regulate the pacing rate according to the Closed-Loop Stimulation (CLS) principle. The physician can program only the lower and upper rate limits, while the internal rate responsive parameters are continually adjusted to changing patient conditions. Seventy-two patients with sinus node disease were enrolled in the multicenter Rate Behavior of the Pacing System Inos (2) CLS during Daily Life (RAPID) study to evaluate the appropriateness of CLS rates during daily activities and the long-term stability of the system. The pacemakers clearly differentiated between climbing stairs, descending stairs, and slow walking, with the corresponding peak rates of 104 +/- 18, 95 +/- 15, and 88 +/- 11 beats/min, respectively (P < 0.001 for any pair of activities). The peak CLS rate during the color-word test was significantly higher than that at rest (80 +/- 8 vs 67 +/- 7 beats/min, P = 0.002). The 24-hour heart rate trends retrieved from the pacemaker memory at 3, 6, and 12 months after implantation appeared appropriate in all patients except for two whose pacing rates were occasionally too fast during the night. Mean diurnal and nocturnal rates determined at 3-month, 6-month, and 12-month examinations fluctuated only slightly, from 74.6-75.3 beats/min (diurnal,P = NS) and from 67.0-68.1 beats/min (nocturnal,P = NS), indicating a satisfactory long-term stability of the system. The incidence of atrial pacing events during the entire follow-up was 82 +/- 18%. A 6.5-8.3 beats/min difference, on average, between day and night (P < 0.001)and distinction between different daily activities seem to evidence sensitivity of the automatic CLS-driven pacemakers to physiological demands despite minimum programming requirements.

Influence of Patient’s Exercise Tolerance on Exercise Heart Rate in Closed Loop Stimulation vs. Accelerometer-based Rate Adaptive Pacing

“…Although AS is specifically designed to support physical activity associated with thoracic movement, CLS is not inferior for this kind of activity and is superior to AS during other forms of exercise, like cycling, mental exertion, or emotional stress [5][6][7][8][9][10]14]. In the randomized crossover PROVIDE study, twice as many chronotropically incompetent patients preferred CLS over AS [5].…”

“…In the CLS mode, the pacemaker couples the pacing rate to the myocardial contraction dynamics by measuring ventricular impedance variation [6][7][8]. As cardiac contractility is regulated by the autonomic nervous innervation, CLS is integrated into the natural cardiovascular control loop and responds to physical, mental, and emotional stress [5,[7][8][9][10].…”

“…As cardiac contractility is regulated by the autonomic nervous innervation, CLS is integrated into the natural cardiovascular control loop and responds to physical, mental, and emotional stress [5,[7][8][9][10]. …”

“…If the hypothesis turned to be true, it would imply that CLS is not only more sensitive to various kinds of stress [5,[7][8][9][10] but that it is also more specific than AS during physical exertion. The hypothesis was tested at 1 month, using symptom classification made at enrolment (NYHA I-like [higher exercise tolerance] vs. NYHA II-or III-like [lower exercise tolerance]) ( Table 1).…”

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

“…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.…”