Catheter Proximity Detection Using Distal Reference Electrode
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Solution Overview
Problem
Existing techniques for estimating the proximity of catheter electrodes to tissue, particularly for large distal end assemblies, face challenges in sensitivity, as impedances relative to reference electrodes may not be sufficient to accurately detect tissue proximity.
Innovation Solution
The introduction of an effective distal reference electrode at the assembly's distal end, in addition to a proximal ring electrode, enhances the coverage of proximity sensing. An AC signal generator applies an electric field between the distal and proximal reference electrodes, increasing impedance as the assembly approaches tissue, allowing for more accurate proximity estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single proximal reference electrode is used for impedance measurements, then the device complexity is reduced, but the measurement precision and spatial coverage of tissue proximity indication deteriorate
Solution Approach 1:
The reference electrode function is segmented into multiple spatially distributed reference electrodes (proximal reference electrode at the catheter hub and distal reference electrode at the distal end of the expandable assembly). This segmentation allows impedance measurements to be performed from multiple locations, improving spatial coverage and measurement precision for determining functional electrode proximity to tissue.
Solution Approach 2:
The measurement system transitions from a single-point reference (proximal only) to a distributed reference system adding the distal dimension. By placing reference electrodes at both proximal and distal ends of the assembly, the system creates a multi-dimensional measurement framework that enhances the ability to detect tissue proximity across the entire functional electrode array.
2Productivity
If the distal end assembly is made large to accommodate multiple functional electrodes, then the productivity and coverage of mapping procedures is improved, but the difficulty of detecting tissue proximity increases due to reduced impedance sensitivity
Solution Approach 1:
The large distal end assembly is segmented into multiple functional electrodes, each capable of independent impedance measurement. By combining multiple measurement points across the expanded assembly with proximal and distal reference electrodes, the system maintains high detection sensitivity despite the large overall size and number of electrodes.
Solution Approach 2:
The distal reference electrode acts as an intermediary measurement point between the functional electrodes at the distal end and the proximal reference electrode. This intermediary enables accurate impedance-based proximity detection for distal functional electrodes by providing a local reference that accounts for the electrical properties of the surrounding medium at the distal location.
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 solution improves the spatial coverage and accuracy of tissue proximity indication (TPI) by enhancing the sensitivity of impedance measurements, effectively addressing the limitations of previous methods.
Implementation Method 1
measuring a resulting AC signal between the functional electrode and the given electrode... determining, for at least one given functional electrode from among the plurality of functional electrodes, a proximity of the functional electrode to wall tissue
Data Source
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AI summary
A system includes a catheter, a signal generator, an interface, and a processor. The catheter includes an expandable distal-end assembly including (i) a plurality of functional electrodes that are at least partially external to an inner volume of the assembly, the functional electrodes configured to be placed in contact with wall tissue of a cardiac chamber, (ii) a proximal reference electrode located at a proximal end of the assembly externally to the inner volume, and (iii) a distal reference electrode located at a distal edge of the expandable assembly externally to the inner volume. The signal generator is configured to generate the AC signal between the proximal and distal reference electrodes. The interface is configured to sense the resulting electrical AC signal. The processor is configured to, based on the sensed AC signals, determine, for at least one given functional electrode, a proximity of the electrode to the wall tissue.