Methods and devices for accurately classifying cardiac activity
First Claim
1. A method of cardiac signal analysis in an implantable medical device (IMD), the IMD including a number of implantable electrodes and operational circuitry for analyzing signals obtained via the implantable electrodes, the IMD further comprising a therapy delivery capacitor and a charging circuit associated with the therapy delivery capacitor, the charging circuit configured to selectively charge the therapy delivery capacitor to prepare for delivery of cardiac cardioversion or defibrillation therapy when enabled by the operational circuitry, the method comprising:
- the operational circuitry detecting a set of events in a signal including detecting a plurality of cardiac cycles;
the operational circuitry analyzing the set of events to determine whether any of the set of events meets criteria for likely overdetection and applying flags to each event of a subset of the events which meet criteria for likely overdetection;
the operational circuitry generating a corrected interval for each event in the subset of events, wherein the corrected interval includes an interval preceding an event from the subset of events combined with an interval following the event;
the operational circuitry determining that a cardiac arrhythmia is likely occurring using at least one corrected interval; and
the operational circuitry, in response to determining that the cardiac arrhythmia is likely occurring, performing a charge confirmation analysis comprising analyzing a pattern of flags within the set of events to determine whether therapy should be delivered.
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Abstract
Methods, systems, and devices for signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In illustrative examples, captured data including detected events is analyzed to identify likely overdetection of cardiac events. In some illustrative examples, when overdetection is identified, data may be modified to correct for overdetection, to reduce the impact of overdetection, or to ignore overdetected data. New methods for organizing the use of morphology and rate analysis in an overall architecture for rhythm classification and cardiac signal analysis are also discussed.
267 Citations
18 Claims
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1. A method of cardiac signal analysis in an implantable medical device (IMD), the IMD including a number of implantable electrodes and operational circuitry for analyzing signals obtained via the implantable electrodes, the IMD further comprising a therapy delivery capacitor and a charging circuit associated with the therapy delivery capacitor, the charging circuit configured to selectively charge the therapy delivery capacitor to prepare for delivery of cardiac cardioversion or defibrillation therapy when enabled by the operational circuitry, the method comprising:
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the operational circuitry detecting a set of events in a signal including detecting a plurality of cardiac cycles; the operational circuitry analyzing the set of events to determine whether any of the set of events meets criteria for likely overdetection and applying flags to each event of a subset of the events which meet criteria for likely overdetection; the operational circuitry generating a corrected interval for each event in the subset of events, wherein the corrected interval includes an interval preceding an event from the subset of events combined with an interval following the event; the operational circuitry determining that a cardiac arrhythmia is likely occurring using at least one corrected interval; and the operational circuitry, in response to determining that the cardiac arrhythmia is likely occurring, performing a charge confirmation analysis comprising analyzing a pattern of flags within the set of events to determine whether therapy should be delivered. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An implantable cardiac stimulus device (ICSD) comprising electrodes for capturing data from a recipient of the ICSD and operational circuitry coupled to the electrodes to analyze signals captured from the recipient, the ICSD also comprising a therapy delivery capacitor and a charging circuit associated with the therapy delivery capacitor, the charging circuit configured to selectively charge the therapy delivery capacitor to prepare for delivery of cardiac cardioversion or defibrillation therapy when enabled by the operational circuitry, wherein the operational circuitry is configured to perform the following:
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detecting events in a signal captured from the electrodes, including detecting a plurality of cardiac cycles; analyzing the detected events to determine whether overdetection is likely occurring and applying a flag to detected events which meet criteria for likely overdetection; determining that a cardiac arrhythmia is likely occurring; in response to determining that the cardiac arrhythmia is likely occurring, performing a charge confirmation analysis comprising analyzing any flags applied to the detected events to identify a pattern of flags, wherein the operational circuitry is configured to withhold charging in response to identifying a pre-specified pattern of flags; and enabling the charging circuit if the charge confirmation analysis is satisfied;
ordetecting an additional event if the charge confirmation analysis is not satisfied and again performing the steps of determining whether a cardiac arrhythmia is likely occurring and, if so, performing the charge confirmation analysis on a new set of detected events including the additional detected event. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An implantable cardiac stimulus device (ICSD) comprising a canister housing operational circuitry, the canister configured for coupling to a lead having one or more electrodes, the operational circuitry configured to receive a signal from a plurality of electrodes when a lead is coupled to the canister, the ICSD also comprising a therapy delivery capacitor and a charging circuit associated with the therapy delivery capacitor, the charging circuit configured to selectively charge the therapy delivery capacitor to prepare for delivery of cardiac cardioversion or defibrillation therapy when enabled by the operational circuitry, wherein the operational circuitry is configured to perform the following:
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detecting events in a signal captured from the electrodes, including detecting a plurality of cardiac cycles; analyzing the detected events to determine whether overdetection is likely occurring and applying a flag to detected events which meet criteria for likely overdetection; determining that a cardiac arrhythmia is likely occurring; in response to determining that the cardiac arrhythmia is likely occurring, performing a charge confirmation analysis comprising analyzing any flags applied to the detected events to identify a pattern of the flags within a set of detected events to determine whether therapy should be delivered, wherein the operational circuitry is configured to withhold charging in response to identifying a pre-specified pattern of flags; and enabling the charging circuit if the charge confirmation analysis is satisfied;
ordetecting an additional event if the charge confirmation analysis is not satisfied and again performing the steps of determining whether a cardiac arrhythmia is likely occurring and, if so, performing the charge confirmation analysis on a new set of detected events including the additional detected event. - View Dependent Claims (15, 16, 17, 18)
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Specification