Phrenic Nerve Detection in Cardiac Pacing via Respiratory Phase Analysis
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Solution Overview
Problem
Cardiac pacing therapies often unintentionally stimulate the phrenic nerve, leading to uncomfortable side effects and interference with breathing, due to the proximity of pacing leads to the phrenic nerve and variability in nerve activation thresholds during different respiratory phases.
Innovation Solution
A cardiac rhythm management system that employs phrenic nerve activation detection algorithms to characterize and avoid phrenic nerve activation by identifying respiratory phases using impedance sensors and analyzing accelerometer data, adjusting pacing pulse energy and parameters to minimize nerve stimulation, and performing tests to determine optimal pacing settings that do not activate the phrenic nerve during specific respiratory phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pacing pulse energy is increased to ensure reliable cardiac capture, then cardiac pacing reliability is improved, but phrenic nerve activation risk increases
Solution Approach 1:
The system performs phrenic nerve activation testing before delivering therapeutic pacing pulses. By conducting preliminary tests at different respiratory phases and adjusting pulse energy accordingly, the system identifies safe energy levels that ensure cardiac capture without activating the phrenic nerve, thus resolving the contradiction between reliability and harmful effects
Solution Approach 2:
The system dynamically adjusts pacing pulse energy based on detected respiratory phase. Since phrenic nerve activation thresholds vary during the respiratory cycle, the controller modifies pulse parameters in real-time according to the current respiratory phase, allowing reliable cardiac capture while avoiding phrenic nerve stimulation at critical moments
2Object-affected harmful factors
If pacing parameters are adjusted to avoid phrenic nerve activation, then patient comfort is improved, but cardiac pacing effectiveness may be reduced
Solution Approach 1:
The system segments the respiratory cycle into distinct phases and tests pacing parameters specific to each phase. By dividing the testing into phases (inspiration, expiration, transition), the system identifies the maximum safe pulse energy for each phase, ensuring both patient comfort and effective cardiac pacing without unnecessary energy reduction
Solution Approach 2:
The system changes pacing parameters (pulse energy, amplitude, duration) based on respiratory phase detection. By systematically varying these parameters during testing at different respiratory phases, the system determines optimal settings that maintain cardiac pacing effectiveness while avoiding phrenic nerve activation, thus resolving the contradiction between comfort and effectiveness
3Measurement precision
If phrenic nerve activation testing is performed during all respiratory phases, then detection accuracy is improved, but testing time increases
Solution Approach 1:
The system performs phrenic nerve activation testing periodically at key respiratory phases rather than continuously throughout the entire cycle. By selecting specific phases (inspiration, expiration, and transition points) for testing, the system achieves sufficient detection accuracy while minimizing the total testing time required
Solution Approach 2:
The system performs preliminary testing at representative respiratory phases to identify patterns of phrenic nerve activation. By conducting initial tests at key phases and using the results to guide subsequent testing or therapy delivery, the system achieves accurate detection without requiring exhaustive testing at every possible moment, thus reducing time loss
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
The system effectively characterizes phrenic nerve activation and adjusts pacing parameters to prevent unintended stimulation, ensuring more efficient and comfortable cardiac pacing therapy by identifying and avoiding phrenic nerve activation during respiratory cycles.
Implementation Method 1
identifying inspiration, peak inspiration, and expiration respiration cycle phases using an impedance sensor
Implementation Method 2
analyzing accelerometer data collected during the respiration cycle phases and identifying occurrences of phrenic nerve activation
Data Source
AI summary
The present invention concerns phrenic nerve activation detection algorithms for characterization of phrenic nerve activation and phrenic nerve activation avoidance in cardiac pacing therapy.Various embodiments concern receiving a respiration signal indicative of respiratory activity of the patient, identifying respiratory phases based on the respiration signal, delivering cardiac pacing pulses within each of the identified respiratory phases, receiving a phrenic nerve activation signal indicative of activation of the patient's phrenic nerve, analyzing the phrenic nerve stimulation signal to determine if one or more of the pacing pulses activated the phrenic nerve of the patient, and determining if at least one of the delivered pacing pulses activated the phrenic nerve of the patient based on the phrenic nerve activation signal indicating activation of the patient's phrenic nerve associated with delivery of the at least one cardiac pacing pulse.