Hybrid ECG PLI Filtering for Real-Time T-Wave Detection
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Solution Overview
Problem
Existing methods for removing power line interference (PLI) from electrocardiograms (ECG) signals are inefficient in real-time, causing delays that affect the accuracy of synchronous pacing during cardiac procedures.
Innovation Solution
A hybrid filter system that estimates PLI digitally and cancels it analogously in real-time, using a predictive or feedback loop method to suppress PLI with minimal delay, employing a PLI harmonics estimator and differential amplifier to subtract the interference from the ECG signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If digital filtering methods are used to remove power line interference from ECG signals, then PLI suppression is achieved, but time delay occurs that renders synchronous pacing inaccurate
Solution Approach 1:
The patent replaces digital signal processing (computational/mechanical system) with an analog filtering system that operates in the electrical domain. The analog filter processes the ECG signal in real-time without the time delays inherent in digital sampling, buffering, and computational filtering, thereby maintaining synchronous pacing accuracy while still achieving PLI suppression.
Solution Approach 2:
The patent introduces an analog filter as an intermediary component between the ECG signal source and the digital processing system. This analog filter performs preliminary PLI removal in the analog domain, allowing the subsequent digital system to work with already-cleaned signals, thus avoiding the time delay problem while maintaining effective interference suppression.
2Reliability
If grounding and shielding are used to protect ECG signals from PLI, then signal integrity is maintained, but PLI distortion of T-wave persists
Solution Approach 1:
The patent extracts the power line interference component from the ECG signal using an analog filter designed to specifically target and remove PLI frequencies (50/60 Hz) and their harmonics. By extracting only the interference component and removing it, the T-wave and other physiological signals remain intact without distortion, overcoming the limitations of passive grounding and shielding approaches.
3Measurement precision
If real-time PLI removal is implemented, then T-wave identification accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the PLI removal function into a dedicated analog filter module that operates independently from the main digital ECG processing system. This segmentation allows the complex real-time filtering task to be handled by a specialized hardware component, reducing the complexity burden on the overall system while maintaining high T-wave identification accuracy.
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 reduces PLI in real-time, improving the accuracy of T-wave identification and enabling precise pacing by minimizing time delays in ECG signal processing.
Implementation Method 1
amplifying a difference between the analog PLI cancellation signal and the ECG signal to generate an ECG signal with suppressed PLI
Data Source
AI summary
A power line interference (PLI) suppression method includes receiving an input analog signal superimposed with PLI, and digitally estimating one or more harmonics of the PLI in real-time. Responsively to the one or more digitally estimated harmonics, one or more analog harmonic waveforms are outputted, that match the respective one or more harmonics of the PLI. The input analog signal and the one or more analog harmonic waveforms are received, and the superimposed PLI in the input analog signal is suppressed using the one or more analog harmonic waveforms. An analog output signal is outputted, that corresponds to the input analog signal having the suppressed PLI.