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.
273 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