Implantable Pacing Device Phrenic Nerve Stimulation Detection
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Solution Overview
Problem
Current methods for detecting and reducing phrenic nerve stimulation in cardiac pacing systems are not sufficiently accurate and effective, leading to undesirable side effects such as involuntary diaphragmatic contractions and breathing interference.
Innovation Solution
An implantable medical device that delivers pacing pulses with varying delays within the refractory period of the left ventricle, measures impedance signals in synchronized time windows, and analyzes aggregated signals to detect phrenic nerve stimulation by comparing recorded impedance signals with templates created for different postures, activity levels, and electrode configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If left ventricular pacing is performed via the coronary sinus, then bi-ventricular pacing therapy is provided, but phrenic nerve stimulation occurs causing involuntary diaphragmatic contractions and breathing interference
Solution Approach 1:
The system performs preliminary detection of phrenic nerve stimulation by analyzing impedance signals during and after pacing pulses. By detecting the harmful effect in advance and in real-time, the system can adjust pacing parameters before significant diaphragmatic contraction occurs, thereby maintaining bi-ventricular pacing capability while preventing harmful phrenic nerve stimulation.
Solution Approach 2:
The system continuously monitors impedance signals and uses this feedback to detect phrenic nerve stimulation. Based on the detected impedance changes, the system adjusts pacing pulse parameters (amplitude, width, timing) to reduce or eliminate phrenic nerve stimulation while maintaining effective ventricular pacing therapy.
2Reliability
If pacing pulse amplitude is increased to ensure adequate ventricular stimulation, then pacing threshold is met, but phrenic nerve stimulation is enhanced
Solution Approach 1:
The system dynamically adjusts multiple pacing parameters including amplitude, pulse width, and timing based on real-time impedance signal analysis. By changing these parameters adaptively, the system can achieve adequate ventricular stimulation while minimizing phrenic nerve stimulation, resolving the contradiction between reliability of pacing and harmful effects.
Solution Approach 2:
The system transitions from static pacing parameters to dynamic, real-time adjusted parameters. By making pacing characteristics variable based on detected impedance changes and patient response, the system can optimize the balance between achieving pacing threshold and avoiding phrenic nerve stimulation.
3Measurement precision
If phrenic nerve stimulation detection accuracy is improved by analyzing impedance signals, then PNS detection precision increases, but device complexity increases
Solution Approach 1:
The system segments the impedance signal analysis into distinct phases: during the refractory period, during the pacing pulse, and after the pulse. By dividing the complex detection task into manageable temporal segments, the system achieves high detection accuracy while keeping the processing complexity manageable through structured analysis approaches.
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 enhances the accuracy of phrenic nerve stimulation detection and reduction by identifying specific footprints in impedance signals, allowing for precise adjustment of pacing settings to minimize unwanted stimulation, thereby improving patient comfort and respiratory function.
Implementation Method 1
An impedance measurement module is configured to measure impedance signals in time windows synchronized with the delivery of pacing pulses in the refractory period of the left ventricle
Data Source
AI summary
The present invention provides implantable medical devices for detecting phrenic nerve stimulation. A pacing module is configured to deliver pacing pulses having a predetermined pulse amplitude and/or width within the refractory period of the left ventricle. The pacing pulses are repeatedly delivered during a number of cardiac cycles, and the pacing pulses are delivered at different delays relative to an onset of the refractory period of the left ventricle in different cardiac cycles. An impedance measurement module is configured to measure impedance signals in time windows synchronized with the delivery of pacing pulses in the refractory period of the left ventricle. A phrenic nerve stimulation, PNS, detection module is configured to gather at least one impedance signal from each time window, create aggregated impedance signals using the impedance signals from the different time windows, and analyze the aggregated impedance signals to detect PNS.