Balloon Ablation Electrode Contact Detection Using Stem and Edge Impedance
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Solution Overview
Problem
Existing cardiac ablation catheters struggle to ensure that all ablation electrodes are in full contact with tissue, leading to potential unwanted side effects such as clot formation when electrodes are partially immersed in blood.
Innovation Solution
A system using an expandable frame with ablation electrodes, a stem electrode, and an edge electrode, along with a processor to measure impedances between these electrodes, determines full tissue contact by comparing measured impedances with prespecified values, ensuring all electrodes are in contact before ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-electrode ablation catheters are used to treat cardiac tissue, then treatment effectiveness is improved, but the risk of unwanted side effects like clot formation increases when electrodes are not fully in contact with tissue
Solution Approach 1:
The patent replaces mechanical verification methods with electrical impedance measurements to detect electrode-tissue contact. The system uses impedance measurements between ablation electrodes and reference electrodes to determine contact status, substituting direct mechanical assessment with electrical property detection.
Solution Approach 2:
The patent introduces impedance measurements as an intermediary indicator to infer electrode-tissue contact status. Instead of directly observing physical contact, the system uses impedance values between electrodes as a mediator to determine whether full contact is achieved, enabling indirect verification of contact quality.
2Measurement precision
If impedance measurements are taken between ablation electrodes and reference electrodes to determine contact status, then contact verification accuracy is improved, but device complexity increases due to multiple electrodes and measurement configurations
Solution Approach 1:
The reference electrodes serve multiple functions: they provide a common reference point for impedance measurements between different ablation electrodes, enable determination of contact status, and facilitate calculation of contact metrics. This multi-functionality reduces the need for separate verification systems.
Solution Approach 2:
The patent segments the measurement system into distinct functional components: ablation electrodes for treatment, reference electrodes for measurement, and a computing device for analysis. This segmentation allows each component to be optimized for its specific function while working together as an integrated system.
3Reliability
If multiple impedance measurements are performed between ablation electrodes and reference electrodes, then contact assessment reliability is improved, but measurement time and procedure complexity increase
Solution Approach 1:
The system performs preliminary impedance measurements between ablation electrodes and reference electrodes before initiating ablation treatment. This preliminary assessment establishes baseline contact status, allowing the procedure to proceed efficiently without repeated measurements during treatment.
Solution Approach 2:
The impedance measurements are integrated into the ablation procedure workflow, allowing continuous monitoring of contact status. The system maintains measurement capability throughout the procedure, enabling real-time verification without interrupting the treatment flow.
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
Enhances the safety and effectiveness of multi-electrode ablation treatments by ensuring complete electrode-tissue contact, reducing the risk of side effects.
Implementation Method 1
measuring, with the processor, one or more first impedances between one or more of the ablation electrodes and the stem electrode, and one or more second impedances between one or more of the ablation electrodes and the edge electrode
Data Source
AI summary
A system includes an expandable frame and a processor. The expandable frame includes (i) one or more ablation electrodes disposed over an external surface of the frame and configured to be placed in contact with wall tissue of a cavity of a patient, and (ii) stem and edge electrodes coupled just proximally and just distally to the balloon, respectively. The processor is configured to: (a) measure one or more first impedances between one or more of the ablation electrodes and the stem electrode, (b) measure one or more second impedances between one or more of the ablation electrodes and the edge electrode, and (c) based on the first and second impedances, determine, for at least an ablation electrode from among the one or more ablation electrodes, whether the ablation electrode is in physical contact with the wall tissue.