Implantable medical devices using heuristic filtering in cardiac event detection
First Claim
1. A method of maintaining a baseline for sensing purposes performed by an implantable cardiac stimulus device (ICSD), the ICSD comprising at least a plurality of sensing electrodes for capturing cardiac signals, the method comprising:
- observing a condition likely to change a sensing baseline for the ICSD; and
performing a dynamic baseline correction of a signal acquired using the sensing electrodes by setting an initial dynamic adjustment period and performing each of the following steps several times;
a) repeatedly performing a sensing baseline adjustment protocol at intervals defined by the dynamic adjustment period; and
b) observing a distance between the sensing baseline and a desired quiescent point and modifying the dynamic adjustment period in response to the observed distance between the sensing baseline and desired quiescent point.
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Abstract
Methods for performing cardiac signal analysis in an implanted medical device, and devices configured to perform illustrative methods of cardiac signal analysis. A cardiac signal is captured by an implanted device using implanted electrodes and, during at least certain conditions, the cardiac signal undergoes heuristic filtering. In some embodiments, heuristic filtering is achieved by modifying a signal or value that is used as an indicator of received signal amplitude. In an illustrative example, the heuristic filtering includes periodically incrementing or decrementing the signal or value toward a desired quiescent point, where the heuristic filter period is significantly longer than the sampling period for the signal itself. In another illustrative example, the heuristic filter frequency can be adjusted dynamically to keep the signal average near the desired quiescent point.
27 Citations
20 Claims
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1. A method of maintaining a baseline for sensing purposes performed by an implantable cardiac stimulus device (ICSD), the ICSD comprising at least a plurality of sensing electrodes for capturing cardiac signals, the method comprising:
- observing a condition likely to change a sensing baseline for the ICSD; and
performing a dynamic baseline correction of a signal acquired using the sensing electrodes by setting an initial dynamic adjustment period and performing each of the following steps several times;a) repeatedly performing a sensing baseline adjustment protocol at intervals defined by the dynamic adjustment period; and b) observing a distance between the sensing baseline and a desired quiescent point and modifying the dynamic adjustment period in response to the observed distance between the sensing baseline and desired quiescent point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 14, 15, 16)
- observing a condition likely to change a sensing baseline for the ICSD; and
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9. An implantable cardiac stimulus device (ICSD) comprising a plurality of sensing electrodes coupled to operational circuitry that includes signal conditioning and amplification circuits and a controller, wherein the operational circuitry is configured to perform a method of establishing data for cardiac event detection comprising:
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observing a condition likely to change a sensing baseline for the ICSD; and performing a dynamic baseline correction by setting an initial dynamic adjustment period and performing each of the following steps several times; a) repeatedly performing a sensing baseline adjustment protocol at intervals defined by the dynamic adjustment period; and b) observing a distance between the sensing baseline and a desired quiescent point and modifying the dynamic adjustment period in response to the observed distance between the sensing baseline and desired quiescent point. - View Dependent Claims (10, 11, 12, 13, 17, 18, 19, 20)
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Specification