Gated ECG Sampling During RF Ablation Zero-Crossing
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Solution Overview
Problem
During radio frequency (RF) ablation therapy, the strong RF ablation signal interferes with the detection of electrocardiogram (ECG) signals due to leakage, corrupting the ECG signals and requiring costly high-attenuation filters to mitigate this interference.
Innovation Solution
The system employs detection circuitry to identify time intervals around the zero crossings of the RF ablation signal, where the amplitude is minimal, and uses gating circuitry to sample the ECG signal only during these intervals, reducing interference and eliminating the need for costly filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-attenuation filters are used to mitigate RF interference with ECG signals, then ECG signal detection quality is improved, but device cost and complexity increase
Solution Approach 1:
The system uses periodic gating synchronized with the RF ablation waveform, sampling ECG signals only during zero-crossing intervals when RF interference is minimal. This periodic sampling approach eliminates the need for complex continuous filtering while achieving clean ECG signal detection.
Solution Approach 2:
The patent introduces an intermediary gating mechanism that mediates between the RF ablation signal and ECG detection. The gate acts as a temporal filter, allowing ECG signals to pass through only during safe time windows when RF interference is absent, thereby avoiding direct conflict between the two signals.
2Loss of information
If continuous ECG sampling is performed during RF ablation, then complete ECG signal data is acquired, but RF signal leakage corrupts the ECG measurements
Solution Approach 1:
The system implements periodic sampling of ECG signals synchronized with the RF ablation cycle, acquiring data only during zero-crossing intervals when RF interference is minimal. This approach balances signal completeness with interference avoidance by strategically selecting sampling windows.
Solution Approach 2:
The system preliminarily identifies and marks the zero-crossing intervals of the RF waveform before ECG sampling occurs. This preliminary characterization of safe time windows allows the ECG acquisition to proceed without corruption, as the sampling gate is pre-synchronized with the RF cycle.
3Power
If RF ablation energy is delivered at high power, then ablation effectiveness is improved, but ECG signal corruption increases
Solution Approach 1:
The system allows high-power RF ablation to proceed continuously while periodically gating the ECG sampling to occur only during zero-crossing intervals. This decouples the RF power delivery from ECG acquisition timing, enabling high-power ablation without compromising ECG signal quality.
Solution Approach 2:
The gating mechanism serves as an intermediary that separates the high-power RF ablation process from ECG detection. By introducing this temporal mediator, the system allows maximum RF power delivery while preventing signal corruption through selective sampling during interference-free intervals.
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 separates the ECG signal from the RF ablation signal, providing a clean ECG signal with minimal additional filtering, enhancing the detection of cardiac signals during RF ablation therapy.
Implementation Method 1
detection circuitry configured to detect an RF ablation signal
Implementation Method 2
gating circuitry configured to gate an ECG signal such that the ECG signal is sampled only during the identified time intervals
Data Source
Figure 1
Figure 2A~3
AI summary
An apparatus includes detection circuitry and gating circuitry. The detection circuitry is configured to sense a radio frequency (RF) ablation signal that is applied to a heart by an intra-body probe, and to identify time intervals during which an amplitude of an ablation signal is within a predefined window. The gating circuitry is configured to gate an electrocardiogram (ECG) signal acquired in the heart, such that the ECG signal is sampled only within the identified time intervals.