Survey of a New Era in Cardiac Pacing

Abstract

A new generation of cardiac pacemakers can adaptively increase pacing rate by using a biophysical sensor to measure a physiological quantity which is related to the need for increased heart rate. The increased heart rate has proven beneficial to patients during periods of metabolic stress and is demonstrated by increased exercise tolerance, higher cardiac output and a greater sense of well-being. In practice, rate adaption requires an appropriate biophysical parameter, a reliable implantable sensor, and a suitable algorithm to determine pacing rate on the basis of the sensed parameter. Some biophysical quantities are more physiologic, such as blood temperature, respiration, ventricular pressures, and stroke volume; others are less physiologic, such as body vibration. Laboratory and clinical studies were reviewed to provide this overview of current trends. Though the practical implementation of these pacemakers is still limited by the availability of implantable sensors with proven reliability, rate-adaptive pacemakers represent a significant advancement in medical technology.