Implantable Cardiac Device Sensing Parameter Adjustment
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Solution Overview
Problem
Implantable medical devices (IMDs) often incorrectly interpret cardiac activity signals, leading to false declarations of arrhythmias due to oversensing or undersensing R-waves, which can result in unnecessary administration of therapies and impact patient quality of life.
Innovation Solution
A computer-implemented method and system that utilize motion data to adjust cardiac activity sensing parameters, specifically the sensitivity profile, to reduce false arrhythmia detection. This involves obtaining motion data indicative of posture or respiration, analyzing it to determine if it caused R-wave undersensing or oversensing, and automatically adjusting the sensing parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed sensitivity sensing parameters are used in IMDs, then device simplicity is maintained, but false arrhythmia detection occurs due to oversensing or undersensing of R-waves
Solution Approach 1:
The patent implements dynamic adjustment of sensing parameters based on detected motion states. The IMD transitions between different sensitivity profiles (first, second, and third sensitivity) according to the patient's activity level detected by motion sensors. This allows the device to adapt to changing physiological conditions without requiring complex manual programming, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The system performs self-adjustment of sensing parameters based on autonomously detected motion data. The IMD automatically identifies its own motion state and selects appropriate sensitivity levels without external intervention. This self-service capability improves detection accuracy while maintaining device simplicity, as the adjustment process is fully automated within the implantable device.
2Measurement precision
If sensitivity is increased to detect weak R-waves, then undersensing is reduced, but oversensing of noise increases leading to false arrhythmia declarations
Solution Approach 1:
The patent employs dynamic sensitivity adjustment where the sensing threshold adapts based on motion state. During high activity states, the system uses lower sensitivity to avoid oversensing motion artifacts as arrhythmias. During rest states, higher sensitivity is applied to detect weak R-waves. This dynamic approach resolves the contradiction between measurement precision and false declarations.
Solution Approach 2:
The system changes sensing parameters (sensitivity levels) based on detected motion characteristics. Three distinct sensitivity profiles are implemented corresponding to different activity states. This parameter adaptation allows optimal R-wave detection while minimizing false positives from motion-related noise, addressing the contradiction between precision and false declarations.
3Reliability
If multiple sensitivity profiles are implemented to account for motion states, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent uses a single motion sensor system to perform multiple functions: detecting activity level, determining posture state, and triggering appropriate sensitivity profile selection. This multi-functionality approach improves detection reliability across varying conditions while minimizing the increase in device complexity, as one sensor system serves multiple purposes rather than requiring separate systems for each function.
Solution Approach 2:
The IMD autonomously monitors its own motion state and automatically selects appropriate sensing parameters without external control. The device self-manages the complexity of multiple sensitivity profiles by implementing automated state-dependent switching. This self-service mechanism improves reliability while containing complexity within the device's autonomous operation capabilities.
Data Source
AI summary
Computer implemented methods and systems are provided that comprise, under control of one or more processors of a medical device, where the one or more processors are configured with specific executable instructions. The methods and systems obtain motion data indicative of at least one of a posture or a respiration cycle; obtain cardiac activity (CA) signals for a series of beats; identify whether a characteristic of interest (COI) from at least a first segment of the CA signals exceeds a COI limit; analyze the motion data to determine whether at least one of the posture or respiration cycle at least in part caused the COI to exceed the COI limit. Based on the analyzing operation, the methods and systems automatically adjust a CA sensing parameter utilized by the medical device to detect R-waves in subsequent CA signals; and detect an arrhythmia based on a presence or absence of one or more of the R-waves in at least a second segment of the CA signals.