Use of significant point methodology to prevent inappropriate therapy
First Claim
1. An apparatus comprising:
- a cardiac signal sensing circuit configured to provide a sensed electrical cardiac signal representative of cardiac activity of a subject;
a sampling circuit coupled to the cardiac signal sensing circuit;
a therapy circuit, configured to provide one or more of high-energy cardioversion shock therapy, high-energy defibrillation shock therapy, and anti-tachycardia pacing (ATP) to the heart; and
a controller communicatively coupled to the sampling circuit and the therapy circuit, wherein the controller includes;
a detection module configured to detect tachyarrhythmia using the cardiac signal; and
a signal analysis module configured to;
establish significant points (SPs) of the sampled cardiac signal, wherein an SP corresponds to a time of occurrence of a turn encountered in the cardiac signal;
perform autocorrelation of the SPs in an SP domain;
perform a second autocorrelation of the SP autocorrelation;
calculate a number of SPs per heart beat from an SP shift that produces a peak in the second autocorrelation; and
estimate heart rate during the tachyarrhythmia using the number of SPs per heart beat; and
determine a likelihood of the presence of noise in the cardiac signal using the SPs,and wherein the controller is configured to select a therapy for delivery by the therapy circuit in response to the tachyarrhythmia detection and to modify the selected therapy according to the heart rate estimation and the determined likelihood of noise.
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Abstract
An apparatus example comprises a cardiac signal sensing circuit configured to provide a sensed cardiac signal representative of cardiac depolarization events of a subject, a sampling circuit coupled to the cardiac signal sensing circuit, a therapy circuit, and a controller communicatively coupled to the sampling circuit and the therapy circuit. The controller includes a detection module configured to detect tachyarrhythmia using the cardiac signal and a signal analysis module configured to establish significant points (SPs) of the sampled cardiac signal, estimate heart rate during the tachyarrhythmia using the SPs, and provide an indication of whether noise is present in the cardiac signal using the SPs. The controller is configured to select a therapy for delivery by the therapy circuit in response to the tachyarrhythmia detection and to modify the selected therapy according to the heart rate estimation and the noise indication.
73 Citations
18 Claims
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1. An apparatus comprising:
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a cardiac signal sensing circuit configured to provide a sensed electrical cardiac signal representative of cardiac activity of a subject; a sampling circuit coupled to the cardiac signal sensing circuit; a therapy circuit, configured to provide one or more of high-energy cardioversion shock therapy, high-energy defibrillation shock therapy, and anti-tachycardia pacing (ATP) to the heart; and a controller communicatively coupled to the sampling circuit and the therapy circuit, wherein the controller includes; a detection module configured to detect tachyarrhythmia using the cardiac signal; and a signal analysis module configured to; establish significant points (SPs) of the sampled cardiac signal, wherein an SP corresponds to a time of occurrence of a turn encountered in the cardiac signal; perform autocorrelation of the SPs in an SP domain; perform a second autocorrelation of the SP autocorrelation; calculate a number of SPs per heart beat from an SP shift that produces a peak in the second autocorrelation; and estimate heart rate during the tachyarrhythmia using the number of SPs per heart beat; and determine a likelihood of the presence of noise in the cardiac signal using the SPs, and wherein the controller is configured to select a therapy for delivery by the therapy circuit in response to the tachyarrhythmia detection and to modify the selected therapy according to the heart rate estimation and the determined likelihood of noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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sampling a sensed cardiac signal using a medical device that delivers at least one of high-energy cardioversion, high-energy defibrillation shock therapy, and anti-tachycardia pacing (ATP), wherein the sensed cardiac signal is an electrical signal representative of cardiac activity of a subject; detecting tachyarrhythmia using the cardiac signal; and
, in response to the tachyarrhythmia detection;selecting a therapy for delivery by the medical device; establishing significant points (SPs) of the sampled cardiac signal, wherein an SP corresponds to a turn encountered in the cardiac signal; estimating heart rate during the tachyarrhythmia using the SPs, wherein estimating heart rate using the SPs includes; performing autocorrelation in an SP domain; performing a second autocorrelation of the SP autocorrelation; and calculating a number of SPs per heart beat from an SP shift that produces a peak in the second autocorrelation; determining a likelihood of a presence of noise in the cardiac signal using the SPs; and modifying the selected therapy according to the rate estimation and the determined likelihood of noise. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
wherein modifying the selected therapy includes withholding delivery of the selected therapy when the probability of noise is above a noise probability threshold value and the heart rate estimated using the SPs differs by more than a specified threshold value from the heart rate determined from the sensed cardiac signal.
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18. The method of claim 11,
wherein detecting tachyarrhythmia using the cardiac signal includes detecting tachyarrhythmia when heart rate determined from the cardiac signal exceeds a tachyarrhythmia detection rate threshold or interval threshold; - and
wherein modifying the selected therapy includes withholding delivery of the selected therapy when the probability of noise is above a noise probability threshold value, the heart rate estimated using the SPs differs by less than a specified threshold value from the heart rate determined from the sensed cardiac signal, and the heart rate estimated using the SPs is less than a lowest tachyarrhythmia detection rate zone.
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Specification