IEGM Signal Noise Compensation via Feedback Circuitry
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Solution Overview
Problem
Electrical noise significantly interferes with the recording of intracardiac electrogram (IEGM) signals during cardiac electrophysiological procedures, particularly due to noise pickup in cables between catheters and external recording systems, which complicates the interpretation of small electrophysiological signals.
Innovation Solution
An electrical activity measurement system with signal processing circuitry and feedback circuitry that senses and compensates for electrical noise by generating a compensatory signal, transforming time windows of the feedback signal into the frequency domain to analyze noise frequencies, and adding a 180-degree out-of-phase compensatory signal to the IEGM signal to cancel out noise before it is added to the signal in the cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cable is used to transmit the IEGM signal from the catheter to the external recording system, then the signal can be recorded externally, but electrical noise is picked up by the cable which degrades the signal quality
Solution Approach 1:
The patent applies preliminary action by predicting and compensating for cable noise before it degrades the signal. The system characterizes the cable's noise properties in advance and uses this information to pre-process the signal, applying inverse filtering or noise cancellation algorithms that remove anticipated noise components before they can corrupt the IEGM signal.
Solution Approach 2:
The patent implements feedback by continuously monitoring the signal quality and adjusting noise cancellation parameters in real-time. The system measures the actual noise present in the transmitted signal and feeds this information back to the processing circuitry, which then adapts its filtering algorithm to optimally cancel the identified noise while preserving the genuine physiological signal.
2Measurement precision
If signal processing circuitry is added to compensate for cable noise, then noise reduction is achieved, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediary processing circuit that acts as a mediator between the simple cable transmission and the complex noise cancellation algorithms. This intermediary component performs intermediate signal conditioning, such as analog filtering or amplification, that simplifies the subsequent digital processing requirements and reduces the overall system complexity while maintaining effective noise reduction.
Solution Approach 2:
The patent uses copying by creating a reference copy of the noise signal through a separate test measurement or through modeling the cable's electrical characteristics. This reference copy is then used to generate cancellation signals without requiring complex real-time analysis of the main IEGM signal, thereby simplifying the processing circuitry while achieving effective noise cancellation.
3Measurement precision
If the IEGM signal is processed before transmission, then noise compensation can be applied, but the signal processing time increases
Solution Approach 1:
The patent applies preliminary action by performing signal characterization and preprocessing operations before the actual IEGM signal transmission. The system pre-calculates filtering parameters, characterizes cable properties, and prepares noise cancellation algorithms in advance, so that when the actual signal arrives, minimal real-time processing is required, thus reducing time loss while maintaining noise compensation effectiveness.
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 effectively reduces noise interference, improving the signal-to-noise ratio and ensuring more accurate recording of IEGM signals by compensating for noise that would otherwise be introduced in the cable, thereby enhancing the clarity and reliability of electrophysiological data.
Implementation Method 1
adding a 180-degree out-of-phase compensatory signal to the IEGM signal to cancel out noise
Data Source
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AI summary
In one embodiment, an electrical activity measurement system includes a catheter to be inserted into a body part and including at least one electrode, signal processing circuitry coupled to receive an intracardiac electrogram (IEGM) signal from the at least one electrode and process the IEGM signal for output to a recording apparatus via a cable, which picks up surrounding electrical noise, and feedback circuitry configured to receive at least some of the electrical noise picked up by the cable, and provide a feedback signal indicative of the received electrical noise to the signal processing circuitry, which is configured to compensate at least partially for the electrical noise, which is not yet in the IEGM signal but will be added to the IEGM signal in the cable, responsively to the feedback signal to produce a noise-compensated IEGM signal for output to the recording apparatus via the cable.