R-Wave Oversensing Classification in Implantable Cardiac Monitors
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Solution Overview
Problem
Existing implantable medical devices (IMDs) face challenges in accurately distinguishing R-waves from over-sensed P-waves and T-waves, leading to false detections of cardiac arrhythmias and inappropriate therapy delivery, such as shocks, which can deplete batteries and cause patient discomfort.
Innovation Solution
A method and device using a processor to compare R-R interval durations and specific morphological characteristics of R-wave detections with earlier detections to classify false R-wave detections due to T-wave or P-wave oversensing, employing temporal and morphological criteria to differentiate between true and false R-waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ICDs use bipolar intracardiac electrogram signals for rhythm detection, then detection capability is maintained, but far-field EGMs in S-ICDs include significantly large P-waves and T-waves that are erroneously over-sensed as R-waves
Solution Approach 1:
The patent segments the EGM signal analysis into multiple components: detecting candidate R-waves, identifying P-waves and T-waves separately, and analyzing their temporal relationships. By dividing the detection process into distinct stages and comparing signal characteristics at each stage, the system can distinguish true R-waves from oversensed P-waves and T-waves in far-field EGMs
Solution Approach 2:
The patent introduces an intermediary analysis layer that examines the temporal relationships between detected waves. By analyzing the timing intervals between P-waves, T-waves, and candidate R-waves, and comparing these intervals to expected physiological ranges, the system mediates between the raw signal and final detection decisions to eliminate false positives
2Measurement precision
If R-wave detection threshold is lowered to detect all potential R-waves, then sensitivity increases, but false positive detections increase due to oversensing of P-waves and T-waves
Solution Approach 1:
The patent performs preliminary detection of P-waves and T-waves before making final R-wave detection decisions. By identifying and marking P-waves and T-waves in advance, and then checking whether candidate R-waves coincide with these marked regions, the system can maintain high sensitivity thresholds while filtering out false positives through pre-established temporal criteria
3Object-affected harmful factors
If present P-wave and T-wave detection discriminator techniques are used, then some oversensing is reduced, but they are often unable or inadequate to correctly distinguish P-waves and T-waves from R-waves, leading to false R-wave detections
Solution Approach 1:
The patent adds temporal relationship analysis as an additional dimension to wave discrimination. Instead of relying solely on amplitude or morphology criteria, the system examines the timing relationships between detected waves, comparing intervals to expected physiological ranges. This temporal dimension provides an independent criterion for distinguishing P-waves, T-waves, and R-waves that complements traditional discrimination methods
Data Source
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AI summary
Described herein are methods and devices (801) for determining whether an R-wave detection should be classified as a false R-wave detection due to T-wave oversensing (TWO) or P-wave oversensing (PWO). One such method includes comparing a specific morphological characteristic (e.g., peak amplitude) associated with the R-wave detection to the specific morphological characteristic associated with each R-wave detection in a first set of earlier detected R-wave detections to thereby determine whether first TWO or PWO morphological criteria are met, and in a second set of earlier detected R-wave detections to thereby determine whether second TWO or PWO morphological criteria are met, wherein the second set differs from the first set but may have some overlap with the first set. The method also includes determining whether to classify the R-wave detection as a false R-wave detection, based on whether one of the first or second TWO or PWO morphological criteria are met.