Methods and devices for tachyarrhythmia sensing and high-pass filter bypass
First Claim
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1. A method of operating an implantable cardiac stimulus device, the method comprising:
- capturing cardiac signals between implanted electrodes;
observing whether a tachyarrhythmia is likely occurring; and
selecting and implementing a mode of filtering based upon whether a tachyarrhythmia is likely occurring such that;
a) if no tachyarrhythmia is likely occurring, using a first filtering, mode on the cardiac signal and using the cardiac signal, as filtered using the first filtering mode, to detect whether a cardiac event has occurred;
b) if a tachyarrhythmia is likely occurring, using a second filtering mode on the cardiac signal and using the cardiac signal, as filtered using the second filtering mode, to detect whether a cardiac event has occurred;
wherein the first filtering mode attenuates frequencies likely to contain T-waves of the cardiac signal more than the second filtering mode, and wherein the selecting and implementing a mode of filtering is performed based on whether a tachyarrythmia is likely occurring as follows;
during a first time period, observing that a tachyarrhythmia is not likely occurring and the first filtering mode is used, andduring a second time period observing that a tachyarrhythmia is likely occurring and the second filtering mode is used instead of the first filtering mode.
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Abstract
The present invention, in illustrative embodiments, includes methods and devices for analyzing cardiac signals in an implantable cardiac stimulus system. Within the analysis, a threshold may be defined related to a cardiac event rate. If the cardiac event rate does not exceed the threshold, filtering of captured cardiac signals occurs, including attenuating T-waves. If the cardiac event rate does exceed the threshold, circuitry for analog filtering or programming for digital filtering is bypassed to avoid attenuating low frequency components of the captured cardiac signals.
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Citations
16 Claims
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1. A method of operating an implantable cardiac stimulus device, the method comprising:
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capturing cardiac signals between implanted electrodes;
observing whether a tachyarrhythmia is likely occurring; andselecting and implementing a mode of filtering based upon whether a tachyarrhythmia is likely occurring such that; a) if no tachyarrhythmia is likely occurring, using a first filtering, mode on the cardiac signal and using the cardiac signal, as filtered using the first filtering mode, to detect whether a cardiac event has occurred; b) if a tachyarrhythmia is likely occurring, using a second filtering mode on the cardiac signal and using the cardiac signal, as filtered using the second filtering mode, to detect whether a cardiac event has occurred; wherein the first filtering mode attenuates frequencies likely to contain T-waves of the cardiac signal more than the second filtering mode, and wherein the selecting and implementing a mode of filtering is performed based on whether a tachyarrythmia is likely occurring as follows; during a first time period, observing that a tachyarrhythmia is not likely occurring and the first filtering mode is used, and during a second time period observing that a tachyarrhythmia is likely occurring and the second filtering mode is used instead of the first filtering mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating an implantable cardiac stimulus device comprising:
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capturing cardiac signals from implanted electrodes using a selectable filtering mode; analyzing the cardiac signals to determine whether a tachyarrhythmia is likely occurring; and in response to a determination of whether a tachyarrhythmia is likely occurring based on analysis of captured events, choosing the selectable filtering mode for use in analysis of future cardiac signals in the following manner; a) if no tachyarrhythmia is likely occurring, choosing a first filtering mode and filtering the cardiac signal using the first filtering mode and using the cardiac signal, as filtered by the first filtering mode, to detect whether a cardiac event has occurred; b) if a tachyarrhythmia is likely occurring, choosing a second filtering mode and filtering the cardiac signal using the second filtering mode and using the cardiac signal, as filtered by the second filtering mode, to detect whether a cardiac event has occurred;
wherein;the first filtering mode, if applied to a T-wave of the cardiac signal, attenuates T-waves of the cardiac signal more than the second filtering mode would attenuate T-waves of the cardiac signal, and the method comprises; during a first time period, observing that a tachyarrhythmia is not likely occurring and applying the first filtering mode to the cardiac signal, and during a second time period, observing that a tachyarrhythmia is likely occurring and applying the second filtering mode to the cardiac signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification