| 摘要 |
2110713 9321991 PCTABS00027 A pacemaker capable of automatically adjusting the activity threshold setting of its activity sensor signal processing circuitry to its optimal value is disclosed. In one embodiment, the pacemaker maintains a running average of zero activity time and a cumulative summation of zero activity time over a predetermined history period. Periodically, the pacemaker computes a time difference between the running average of zero activity time and the cumulative summation of zero activity time, and adjusts the activity threshold of the activity sensor signal processing circuitry according to this computation. By basing the adjustment of activity threshold on a long-term average of zero activity time, the effects of cycle-to-cycle variation in sensed zero activity time are minimized. In another embodiment, the pacemaker periodically computes a time difference between a preprogrammed margin value and the cumulative summation of zero activity time. If the time difference is less than the predetermined margin, the activity threshold is increased. If the time difference is greater than the predetermined margin, the activity threshold is decreased.
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