What is the ideal rate-adaptive sensor for patients with implantable cardioverter defibrillators: lessons from cardiac pacing

The development of implantable pacemakers in the clinical setting mirrors the implementation of advanced technical possibilities. In the United States, 83% of all pacemakers implanted in 1996 had rate response as a programmable option. A variety of sensors have been proposed and used for rate control. Among today’s many concepts, accelerometer-controlled pacing is the most widely used rate-adaptive principle. Although the use of a second sensor is currently of proven benefit for only a limited number of patients, the concept of closed-loop pacing—implementing a negative feedback between pacing rate and the control signal—merits further investigation. This is of special importance in defibrillator patients whose myocardial contractility is generally limited. These patients are most sensitive to pacing rates that are too high for a given metabolic situation. The integration of rate-adaptive pacing into defibrillators is a natural consequence of the technical evolution.