Abstract: A method and apparatus for optimizing the performance of a rate-responsive cardiac pacemaker. A pacemaker is provided which is capable of obtaining and storing information about a patient's cardiac function and about a pacemaker's operation during a brief exercise interval. The data collected includes information about the number of cardiac events during each two-second interval of the exercise, as well as the percentage of paced events during each two-second interval. Data reflecting the output of the pacemaker's activity sensor output is also collected for each two second interval of the test. In addition, AV interval data for each cardiac cycle during the test is collected, this data being distinguished according to whether it reflects atrial-pace-to-ventricular-sense or atrial-sense-to-ventricular-sense AV intervals. The disclosed pacemaker is operable in conjunction with an external programming/processing unit, which receives the stored data after the exercise test is concluded.

Abstract: A rate-responsive cardiac pacemaker in which deceleration of the pacing rate is modulated according to recent patient activity or "work". Based on signals provided from an activity sensor in the pacemaker, the pacemaker maintains and periodically recomputes a work value corresponding to the amount of patient activity detected over time. In response to a decrease in or cessation of detected patient activity, the pacemaker reduces the pacing rate, first at a more rapid deceleration rate, then at a lower deceleration rate, and then once again at a more rapid deceleration rate. The length of time during which the pacing rate is reduced at the lower deceleration rate is modulated according to the work value maintained by the pacemaker.