Automatic Adaptation of the Basic Pacing Rate in Response to Minute Ventilation

Abstract

Rate responsive pacing based on minute ventilation (VE) correlates highly with metabolic demand. This type of sensing also recognizes extended periods of rest. The Chorum pacemaker includes a rate responsive algorithm that modulates the basic rate according to phases of activity versus sleep. Forty-six patients (mean age 78 +/- 15), received a Chorum pacemaker for atrioventricular block in 17 cases, sick sinus syndrome in 25, and mixed disorders in 4. Holter monitoring was performed to analyze to heart rate and to examine the circadian adaptation of the minimal pacing rate. The mean basic rate was programmed at 63 +/- 5 beats/min, and the sleep rate at 52 +/- 4 beats/min. Seventeen patients had spontaneous heart rates consistently above the programmed basic rate, and 6 had sustained supraventricular tachyarrhythmias. One-half of the patients had periods of pacing at the programmed sleep rate. The mean diurnal pacing rate was 68 +/- 5 beats/min compared to a mean nocturnal rate of 60 +/- 4 beats/min (P < 0.0001). The average time spent at the basic rate was 37 +/- 30 min (0-110) during daytime (4%), versus 242 +/- 153 min (20-477) at night (45%, P < 0.0001). No adverse effect was observed in this patient population. VE allows a reliable detection of the sleeping periods as well as an adjustment of the basic rate in accordance. Caution is advised in cases of bradycardia dependent tachyarrhythmias.

Automatic Recognition of Abnormal Respiratory Events During Sleep by a Pacemaker Transthoracic Impedance Sensor

“…The prevalence of obstructive sleep apnea may be at least 30% in patients with permanent pacemakers (PMs), 8 and that of SAS may be even higher among patients who also have congestive heart failure. Some rate‐response PMs use measurement of transthoracic impedance to provide an index of minute ventilation (MV) as a modality for rate response in patients with chronotropic incompetence 9 . Acute studies have shown a high correlation between estimated MV and oxygen consumption during exercise tests 10,11 .…”

“…Some rate-response PMs use measurement of transthoracic impedance to provide an index of minute ventilation (MV) as a modality for rate response in patients with chronotropic incompetence. 9 Acute studies have shown a high correlation between estimated MV and oxygen consumption during exercise tests. 10,11 However, transthoracic impedance measurements also can be optimized to track each respiratory cycle and provide estimates of variation in tidal volume.…”

Clinical Evaluation of a Pacemaker Algorithm That Adjusts the Pacing Rate During Sleep Using Activity Variance

“…7,8 Minute ventilation sensors were also used to modulate the basic pacing rate during extended resting periods. [9][10][11] Such a sensor-based approach carries theoretical advantages, especially in individuals who take frequent naps and those who arise in the middle of the night for a trip to the bathroom. This type of a dynamic sleep mode was introduced in Pacesetter Trilogy pacemakers (St. Jude Medical CRMD, Sylmar, CA, USA).…”