ICD T-Wave Oversensing Rejection via Signal Segmentation

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Solution Overview

Problem

Implantable medical devices (IMDs) face challenges in accurately detecting cardiac rhythms due to oversensing of T-wave signals, leading to false detection of shockable rhythms and unnecessary cardioversion/defibrillation shocks.

Innovation Solution

An implantable cardioverter defibrillator (ICD) with extracardiac electrodes analyzes cardiac electrical signals to detect T-wave oversensing (TWOS) by setting signal analysis segments, determining TWOS analysis windows, and classifying segments as non-shockable when TWOS detection criteria are met, thereby preventing unnecessary shocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If extracardiac electrodes are used to monitor cardiac electrical signals, then the device can detect abnormal cardiac rhythms, but T-wave oversensing occurs leading to false detection of shockable rhythms

Engineering Contradiction:

Improvedetection accuracyVSAvoidrhythm classification accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent divides the cardiac signal analysis into distinct time segments: a first time segment for initial shockable rhythm detection, and a second time segment for T-wave oversensing rejection analysis. This segmentation allows the device to separately evaluate different aspects of signal quality and rhythm characteristics without interference, resolving the contradiction between detecting true abnormal rhythms and avoiding false detections from T-wave oversensing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary detection of shockable rhythms in the first time segment before conducting the T-wave oversensing rejection analysis in the second time segment. This preliminary action allows the device to identify potential abnormal rhythms that require further verification, and then use the second segment to confirm whether the detected rhythm is truly shockable or merely a T-wave oversensing artifact.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the device delivers cardioversion/defibrillation shocks upon detecting abnormal rhythms, then life-threatening conditions can be treated, but unnecessary shocks are delivered due to false detection

Engineering Contradiction:

Improvetherapy appropriatenessVSAvoidpatient discomfort from unnecessary shocks

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a T-wave oversensing rejection mechanism as an intermediary step between rhythm detection and shock delivery. This intermediary analysis in the second time segment evaluates whether the detected abnormal rhythm is caused by T-wave oversensing before permitting shock delivery. By inserting this verification layer, the device ensures that only truly shockable rhythms trigger therapy, preventing harmful unnecessary shocks while maintaining appropriate treatment of genuine life-threatening conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3291881B1Implantable medical device with means for determining if shockable rhythm classification criteria are met, including determining t-wave oversensing

Publication Date: 2024.06.26 MEDTRONIC INC

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AI summary

A medical device coupled to extracardiac electrodes is configured to analyze a cardiac electrical signal over a signal analysis segment to determine if shockable rhythm classification criteria are met, determine that TWOS detection criteria are met for the signal analysis segment when a predetermined number of TWOS analysis windows are classified as TWOS, and classify the signal analysis segment as non-shockable in response to determining that the TWOS detection criteria are met.