Phrenic Nerve Stimulation Threshold Detection in Cardiac Pacing
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Solution Overview
Problem
Implanted cardiac pacing systems often experience unintended phrenic nerve stimulation, which can lead to discomfort and require frequent reprogramming, due to variations in anatomical nerve locations and stimulation parameters.
Innovation Solution
A system with a cardiac pulse generator, sensor, and controller that detects phrenic nerve stimulation by analyzing physiological signals, determines the stimulation threshold, and performs a confirmation procedure to accurately identify and adjust pacing output levels to avoid nerve activation, using techniques such as clustering, correlation, and morphological feature analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LV pacing output is increased to ensure cardiac capture, then cardiac pacing reliability is improved, but phrenic nerve stimulation is more likely to occur
Solution Approach 1:
The system automatically adjusts pacing parameters (amplitude, pulse width, voltage) to find optimal settings that ensure cardiac capture while minimizing phrenic nerve stimulation. The controller modifies stimulation parameters based on detected PS beats, dynamically changing electrical parameters to resolve the contradiction between reliable cardiac capture and avoiding nerve stimulation.
Solution Approach 2:
The system uses feedback from PS beat detection to automatically adjust pacing output levels. When PS beats are detected, the controller reduces the pacing amplitude or extends pulse width to eliminate nerve stimulation while maintaining cardiac capture, creating a closed-loop system that resolves the contradiction through continuous monitoring and adjustment.
2Object-affected harmful factors
If manual reprogramming is performed to avoid phrenic nerve capture, then phrenic nerve stimulation is reduced, but device complexity and reprogramming time increase
Solution Approach 1:
The device performs self-adjustment of pacing parameters by automatically detecting PS beats and modifying its own output levels. The controller autonomously reduces amplitude or extends pulse width when PS is detected, eliminating the need for manual clinician reprogramming and reducing device operational complexity despite advanced detection capabilities.
Solution Approach 2:
The automatic feedback mechanism allows the device to self-correct phrenic nerve stimulation issues without external intervention. The system monitors for PS beats and automatically adjusts parameters, replacing complex manual reprogramming procedures with an automated closed-loop control system.
3Object-affected harmful factors
If implantation procedure is modified to avoid phrenic nerve capture, then phrenic nerve stimulation is prevented, but implantation time and procedural complexity increase
Solution Approach 1:
The system performs preliminary automatic detection and adjustment of pacing parameters during or after implantation to prevent phrenic nerve stimulation. By automatically identifying and correcting PS issues without requiring time-consuming manual repositioning or reprogramming, the system prevents nerve stimulation while maintaining efficient implantation procedures.
Solution Approach 2:
Rather than modifying the implantation procedure to reposition electrodes, the system achieves phrenic nerve avoidance through automatic parameter adjustments (amplitude reduction, pulse width extension). This approach prevents PS without requiring additional implantation time or procedural modifications.
4Object-affected harmful factors
If pacing amplitude is reduced to avoid phrenic nerve capture, then phrenic nerve stimulation is decreased, but cardiac capture reliability may be compromised
Solution Approach 1:
The system compensates for reduced pacing amplitude by extending pulse width, maintaining the area under the curve and ensuring adequate cardiac capture energy delivery. This parameter transformation allows amplitude reduction to avoid PS while preserving cardiac capture reliability through increased duration.
Solution Approach 2:
The controller dynamically adjusts pacing parameters in real-time based on detected PS beats. When PS occurs, the system modifies amplitude and/or pulse width to eliminate nerve stimulation while maintaining cardiac capture, creating a dynamic adaptation that resolves the contradiction between avoiding PS and ensuring reliable capture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables automatic and accurate detection of phrenic nerve stimulation, reducing patient discomfort and the need for frequent device reprogramming, while improving the reliability of cardiac pacing therapies by minimizing unwanted nerve activation.
Implementation Method 1
a sensor configured to sense a physiological signal for use in detecting pace-induced phrenic nerve stimulation
Implementation Method 2
a cardiac pulse generator configured to generate cardiac paces to pace the heart
Implementation Method 3
analyze the detected PS beats, if PS beats are detected at the pacing output level, using criteria to determine if the pacing output level can be declared to be the PS threshold
Data Source
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AI summary
In an example of a method, the method includes testing for phrenic nerve stimulation (PS) threshold. If PS beats are detected at the pacing output level, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold. If the pacing output level cannot be declared to be the PS threshold based on the analysis of the PS beat at the pacing output level, performing a PS beat confirmation procedure. The PS beat confirmation procedure may include delivering additional cardiac paces at the pacing output level to generate additional PS beats, and analyzing the detected PS beats using other criteria to determine if the pacing output level can be confirmed as the PS threshold.