RF Ablation Electrode Control for Stray Current Mitigation
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Solution Overview
Problem
In radio-frequency ablation (RFA) procedures, small-diameter balloons with closely spaced electrodes can lead to stray currents due to voltage differences, affecting the ablation outcome, especially in unipolar mode where electrodes are close together, causing unintended current paths and reduced effectiveness.
Innovation Solution
A medical apparatus with a probe having multiple electrodes that applies RF signals in parallel, measuring and adjusting time-varying voltage differences to prevent stray currents by regulating signal amplitudes and phases, allowing for precise control of unipolar and bipolar ablation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF signals are applied simultaneously to multiple closely spaced electrodes, then ablation effectiveness is improved, but stray currents between electrodes increase causing unintended current paths
Solution Approach 1:
The controller measures time-varying voltage differences between electrodes and adjusts RF signal amplitudes and phases to minimize voltage differences between closely spaced electrodes. By maintaining equipotential conditions between adjacent electrodes, stray currents are prevented while allowing simultaneous RF application to multiple electrodes for effective ablation.
Solution Approach 2:
The system continuously measures time-varying voltage differences between electrodes during RF signal application and uses this feedback to dynamically adjust the RF signal parameters. This closed-loop control ensures that voltage differences remain minimal, preventing stray currents while maintaining effective ablation delivery.
2Device complexity
If voltage differences between electrodes are allowed to vary freely, then RF signal delivery is simplified, but unintended current paths are created affecting ablation outcome
Solution Approach 1:
The controller continuously measures voltage differences between electrodes and adjusts RF signal parameters in real-time based on these measurements. This feedback mechanism ensures consistent ablation outcomes by preventing stray currents, while the automated control minimizes the operational complexity for the user.
Solution Approach 2:
The system dynamically adjusts RF signal parameters including amplitude and phase for each electrode based on measured voltage differences. By changing these parameters in real-time, the system maintains optimal current distribution for reliable ablation while the automated parameter adjustment keeps the system easy to operate.
3Manufacturing precision
If electrodes are closely spaced on small-diameter balloons, then procedural precision is improved, but voltage differences cause stray currents reducing effectiveness
Solution Approach 1:
The system specifically targets closely spaced electrodes on small-diameter balloons by measuring and minimizing voltage differences between them. This equipotential approach prevents stray currents in the closely spaced configuration, allowing the procedural precision benefits of small balloons to be realized without the harmful stray current effects.
Solution Approach 2:
The controller applies individualized RF signal adjustments to specific electrode pairs based on their spatial relationships. For closely spaced electrodes where stray currents are a concern, the system locally optimizes voltage differences, while allowing greater flexibility for more distal electrodes, thus maintaining ablation effectiveness throughout the array.
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 ensures effective tissue ablation by minimizing stray currents and allowing flexible control over the depth and extent of ablation lesions, improving the precision and efficacy of RFA procedures.
Implementation Method 1
Radio frequency ablation (RFA) is a medical procedure in which part of the electrical conduction pathways of the heart or other dysfunctional tissue are ablated using the heat generated from radio frequency alternating current
Data Source
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AI summary
A medical apparatus includes a probe, which includes an insertion tube configured for insertion into a body cavity of a patient, and a distal assembly, which is connected distally to the insertion tube and includes a plurality of electrodes, which are configured to contact tissue within the body cavity. An electrical signal generator is configured to apply radio frequency (RF) signals simultaneously to the plurality of electrodes with energy sufficient to ablate the tissue contacted by the electrodes. A controller is coupled to measure time-varying voltage differences between the electrodes and to adjust the RF signals applied to the electrodes responsively to the measured time-varying voltage differences.