Methods and devices for accurately classifying cardiac activity
Inventors
Warren, Jay A. • Sanghera, Rick • Allavatam, Venugopal • Palreddy, Surekha
Assignees
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Publication Number
US-10709379-B2
Publication Date
2020-07-14
Expiration Date
Abstract
Methods, systems, and devices for signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In some 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. Several examples emphasize the use of morphology analysis using correlation to static templates and/or inter-event correlation analysis.
Core Innovation
The described invention provides an implantable medical device with operational circuitry and a plurality of electrodes, including a canister with the operational circuitry and at least one electrode associated therewith. The operational circuitry performs cardiac signal analysis by detecting at least first, second and third detected events when a cardiac signal waveform crosses a threshold defined by a detection profile. The first detected event occurs later in time than the second detected event, and the second detected event occurs later in time than the third detected event.
The operational circuitry compares the first detected event to the second detected event to yield a first comparison score, and compares the first detected event to the third detected event to yield a second comparison score. It then analyzes at least the first and second comparison scores to determine if one of the first, second and third detected events is likely due to overdetection. Overdetection likelihood assessment is further refined by using rule sets for double detection and triple detection, and by determining whether the overdetection is a T-wave.
In the broader therapy decision workflow described in the provided content, the device incorporates the overdetection determination into beat qualification and shockable versus not-shockable determination. When an event is identified as likely due to overdetection, the described operation includes excluding the overdetected data from cardiac rate calculation or inhibiting data correction/discarding based on interval analysis consistency of QT interval estimation and RR interval using formula consistency. The device is also described as including sensing vectors, electrodes, and therapy circuitry with capacitive energy storage, a charger, and delivery circuitry for therapy energy delivery.
Claims Coverage
The document includes two independent claims, an IMD apparatus claim and a method-of-operation claim, with multiple dependent claims that refine how overdetection is identified and what is done with the result. Across the independent claims, there are at least three core inventive features: detecting three temporally ordered detected events using a profile-defined threshold, generating comparison scores from event-to-event comparisons, and analyzing the comparison scores to determine whether one event is likely due to overdetection.
Detection of temporally ordered detected events using a detection profile threshold
The operational circuitry detects at least first, second and third detected events by comparing a cardiac signal from the plurality of electrodes to a threshold defined by a detection profile and declaring a detected event having a signal waveform when the threshold is crossed, wherein the first detected event occurs later in time than the second detected event, and the second detected event occurs later in time than the third detected event.
Generation of comparison scores from first-to-second and first-to-third event comparisons
The operational circuitry compares the first detected event to the second detected event to yield a first comparison score, and compares the first detected event to the third detected event to yield a second comparison score.
Overdetection likelihood determination using comparison-score analysis
The operational circuitry analyzes at least the first and second comparison scores to determine if one of the first, second and third detected events is likely due to overdetection.
Overall, the independent claim coverage centers on detecting three temporally ordered cardiac events via a detection profile threshold, computing comparison scores from event relationships, and using those scores to decide whether one detected event is likely due to overdetection. Dependent claims further specify rule sets for double and triple detection, optionally classify the overdetection as a T-wave, and use the result to exclude an overdetected event from cardiac rate calculation and to support therapy-related decisions.
Stated Advantages
Improves classification accuracy by identifying likely cardiac event overdetection and using the determination within a therapy decision workflow.
Documented Applications
Implantable therapy decision workflows that include beat qualification and determining shockable versus not-shockable based on cardiac signal analysis incorporating overdetection identification.
Arrhythmia-related decision-making that compares a calculated cardiac event rate to arrhythmia rate thresholds and, when indicated, supports charging a capacitive energy-storage system and operating delivery circuitry to deliver therapy energy to a patient.
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