Phrenic Nerve Stimulation Detection Baseline Determination
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Solution Overview
Problem
Implanted cardiac pacing systems often experience unintended phrenic nerve stimulation due to the varying anatomical location of the phrenic nerve relative to the pacing lead, leading to discomfort and the need for frequent device reprogramming to avoid this stimulation.
Innovation Solution
A system comprising a cardiac pulse generator, a sensor, and a phrenic nerve stimulation detector that analyzes physiological signals to detect pace-induced phrenic nerve stimulation by calculating a baseline level and comparing it to sampled signals, allowing for dynamic adjustment and accurate identification of phrenic nerve stimulation events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If left ventricular pacing is used to deliver cardiac resynchronization therapy, then cardiac therapy effectiveness is improved, but unintended phrenic nerve stimulation occurs causing patient discomfort
Solution Approach 1:
The system performs preliminary detection of phrenic nerve stimulation by analyzing physiological signals before they become problematic. The detector continuously monitors for characteristic diaphragm contraction signals associated with phrenic nerve capture, allowing early identification and intervention before discomfort occurs
Solution Approach 2:
The system implements feedback by using the detected phrenic nerve stimulation information to automatically adjust pacing parameters. When phrenic nerve capture is detected, the system modifies pacing voltage, pulse width, or timing to eliminate the harmful stimulation while maintaining effective cardiac resynchronization therapy
2Ease of operation
If pacing parameters are modified to avoid phrenic nerve stimulation, then patient comfort is improved, but detection precision and response time are worsened due to signal variability
Solution Approach 1:
The system employs dynamic baseline determination that continuously adapts to changing physiological conditions. Rather than using fixed thresholds, the baseline is recalculated based on recent signal characteristics, allowing the detection system to maintain high precision even when signal morphology varies due to patient movement, posture changes, or physiological variations
Solution Approach 2:
The system changes detection parameters dynamically based on signal characteristics. The baseline level, detection thresholds, and analysis window parameters are adjusted according to the observed signal variability, ensuring optimal detection accuracy across different physiological states and patient conditions
3Object-affected harmful factors
If manual reprogramming is performed to avoid phrenic nerve stimulation, then stimulation is reduced, but device complexity and clinical staff burden increase
Solution Approach 1:
The system provides self-service by automatically detecting phrenic nerve stimulation and adjusting its own pacing parameters without requiring external intervention. The integrated detector and controller work together to autonomously identify harmful stimulation and implement corrective pacing changes, eliminating the need for manual reprogramming by clinical staff
Data Source
AI summary
Some method examples may include pacing a heart with cardiac paces, sensing a physiological signal for use in detecting pace-induced phrenic nerve stimulation, performing a baseline level determination process to identify a baseline level for the sensed physiological signal, and detecting pace-induced phrenic nerve stimulation using the sensed physiological signal and the calculated baseline level. Detecting pace-induced phrenic nerve stimulation may include sampling the sensed physiological signal during each of a plurality of cardiac cycles to provide sampled signals and calculating the baseline level for the physiological signal using the sampled signals. Sampling the sensed physiological signal may include sampling the signal during a time window defined using a pace time with each of the cardiac cycles to avoid cardiac components and phrenic nerve stimulation components in the sampled signal.