[Motion energy as a control variable for adapting stimulation frequency]

An activity sensing rate-responsive pacing system is presented which adaptively controls heart rate to adjust cardiac output in response to increased metabolic demand, and more optimally restore homeostasis of the intact cardiovascular system. The current use of ventricular demand and DDD universal pacing systems, although rate and multi-parameter and multi-function programmable, are fixed at these programmed settings. These devices are adequate for patients at rest or during moderate exertion, but are suboptimal for physically active patients whose physiology requires increased oxygen supply to meet an increased cardiac demand. In the past, these patients may have experienced fatigue or dyspnea out of proportion to their cardiovascular disease. The Ergos rate-adaptive single- and dual-chamber pacing system is a second generation pulse generator which is rate responsive to a patient's increased physiologic demand by sensing a motion signal which reflects increased work load and the need for a compensating increase in heart rate. Ergos offers increased assistance to patients with sinus bradycardia who may require the rate-responsiveness with the additional advantage of AV synchrony. Clinical results show the effectiveness of the presented sensor control by motion energy for rate adaptive pacing therapy.