Patent ID: 7869877
Filing Date: 2011-01-11
Classification: A61B,A61N

Abstract:
1. A cardiac device, comprising: one or more sensing amplifiers for generating intra-cardiac electrogram signals; a controller for detecting intrinsic cardiac activity and measuring an intrinsic heart rate from the electrogram signals; an activity level sensor interfaced to the controller for measuring a parameter related to a patient's level of physical activity; wherein the controller is programmed to construct a historical record of activity level versus heart rate, referred to as a heart rate response profile; wherein the controller is programmed to compute a heart rate response slope from the heart rate response profile, defined as the ratio of an incremental change in intrinsic rate to an incremental change in measured activity level, and compute the rate of change of the heart rate response slope; wherein the controller is programmed to collect periodic maximum heart rates over time and derive a maximum intrinsic heart rate parameter therefrom indicative of the maximum heart rate the patient is able to attain; a pulse generator for pacing a cardiac chamber through a pacing channel, wherein the controller is programmed to control the delivery of pacing pulses in accordance with a programmed mode; and, wherein the controller is programmed to switch to a rate-adaptive pacing mode if the rate of change of the heart rate response slope and maximum intrinsic heart rate parameters indicate chronotropic incompetence.