Phrenic Stimulation Detection in Cardiac Pacing Devices
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Solution Overview
Problem
Cardiac rhythm management devices face challenges in accurately determining capture and phrenic stimulation thresholds, leading to inefficient pacing and potential undesirable stimulation of the phrenic nerve, which can cause discomfort and interfere with cardiac function.
Innovation Solution
The development of phrenic stimulation algorithms that deliver cardiac pacing pulses with varying parameters to detect phrenic nerve activation, allowing for the determination of phrenic stimulation thresholds and optimization of pacing parameters to avoid undesirable stimulation while ensuring cardiac capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pacing pulse energy is increased to ensure reliable cardiac capture, then cardiac capture reliability is improved, but phrenic nerve stimulation risk increases
Solution Approach 1:
The patent replaces direct electrical sensing of phrenic stimulation with an accelerometer-based mechanical detection system. The accelerometer senses diaphragmatic movement caused by phrenic nerve stimulation, converting a physiological/electrical phenomenon into a mechanical measurement that can be detected and used to adjust pacing parameters.
Solution Approach 2:
The system implements a feedback loop where the accelerometer continuously monitors for diaphragmatic movement, and when phrenic stimulation is detected, the pacing device adjusts the pacing pulse energy to remain below the phrenic stimulation threshold while maintaining adequate cardiac capture.
2Object-affected harmful factors
If pacing parameters are reduced to avoid phrenic nerve stimulation, then phrenic stimulation is reduced, but cardiac capture reliability may deteriorate
Solution Approach 1:
The system dynamically adjusts pacing parameters based on real-time detection of phrenic stimulation thresholds. Rather than using fixed conservative parameters, the device adapts the pacing pulse energy to match the patient's specific phrenic stimulation threshold, optimizing both safety and efficacy.
Solution Approach 2:
The patent changes the pacing pulse energy parameter to operate at or near the phrenic stimulation threshold determined through algorithmic testing, rather than using fixed conservative values. This allows maximization of cardiac capture reliability while maintaining safety margins.
3Productivity
If phrenic stimulation threshold testing is performed to optimize pacing parameters, then pacing efficiency is improved, but device complexity increases
Solution Approach 1:
The device performs self-testing and self-adjustment of pacing parameters using built-in accelerometer sensing and algorithmic threshold determination. The system autonomously characterizes the patient's phrenic stimulation threshold and configures optimal pacing parameters without requiring external programming or complex external testing equipment.
Solution Approach 2:
The patent implements periodic threshold testing and parameter optimization routines that can be performed at scheduled intervals or when specific conditions are met. This allows the device to maintain optimal pacing parameters while managing computational resources and battery power efficiently.
Data Source
AI summary
Approaches for characterizing a phrenic stimulation threshold, a cardiac capture threshold, a maximum device parameter, and a minimum device parameter are described. A plurality of cardiac pacing pulses can be delivered by using a cardiac pacing device, a pacing parameter of the plurality of cardiac pacing pulses being changed between delivery of at least some of the pulses. One or more sensor signals can be evaluated to detect stimulation of the phrenic nerve by one or more of the plurality of cardiac pacing pluses. The evaluation of the one or more sensor signals and the pacing parameter can be compared to determine if a phrenic stimulation threshold is at least one of higher than a maximum device parameter and lower than a minimum device parameter.