Reference Electrode Positioning for Catheter Tissue Proximity
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Solution Overview
Problem
Existing methods for estimating the proximity of catheter electrodes to tissue lack sensitivity and accuracy, particularly in distinguishing between tissue contact and immersion in a blood pool.
Innovation Solution
The proposed solution involves positioning a reference ring electrode externally to the inner volume of the expandable distal assembly, spaced away from tissue contact, and using a processor to estimate proximity based on impedance measurements between the functional electrodes and the reference ring electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference electrode is positioned within the inner volume of the distal-end assembly, then the electrode is distanced from tissue wall, but the sensitivity and accuracy in distinguishing tissue contact from blood immersion is reduced
Solution Approach 1:
The reference ring electrode is extracted from the inner volume of the distal-end assembly and repositioned externally at the base section. This extraction allows the reference electrode to be spaced away from tissue contact while maintaining electrical isolation, thereby improving the sensitivity and accuracy of tissue proximity estimation without increasing device complexity
Solution Approach 2:
The distal-end assembly structure serves as an intermediary element that positions the reference ring electrode externally at the base section. This intermediary positioning ensures the reference electrode remains electrically isolated from tissue contact while maintaining a stable reference potential for impedance measurements, resolving the contradiction between measurement precision and device complexity
2Ease of operation
If the reference electrode is placed in contact with tissue, then impedance measurement is simplified, but the ability to distinguish tissue contact from blood immersion is compromised
Solution Approach 1:
The reference ring electrode is positioned with specific local quality characteristics - located externally at the base section of the distal-end assembly where it is spaced away from tissue contact. This localized positioning provides a stable reference potential while maintaining the ability to distinguish tissue contact from blood immersion through impedance measurements, resolving the contradiction between ease of operation and measurement precision
3Reliability
If the reference electrode is positioned to avoid tissue contact, then electrical path interference is minimized, but the electrode may be harder to position consistently
Solution Approach 1:
The reference ring electrode is preliminarily positioned at the base section of the distal-end assembly during manufacturing, where the structure naturally spaces it away from tissue contact. This preliminary positioning ensures consistent electrical isolation and reliable impedance measurements while simplifying the manufacturing process, as the base section geometry provides a natural reference plane for consistent electrode placement
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 enhances sensitivity and accuracy in determining tissue proximity by minimizing electrical path interference and improving the discrimination between tissue contact and blood immersion.
Implementation Method 1
the reference ring electrode (17) is configured to be coupled with each of the plurality of functional electrodes (26) for generating an electric field between each of the plurality of functional electrodes (26) and the reference ring electrode (17)
Implementation Method 2
Respective impedances are estimated, from the electrical readings, between the functional electrodes (26) and the reference ring electrode (17)
Data Source
AI summary
A catheter includes a shaft having a distal-end and an expandable distal-end assembly configured for insertion into a cavity of an organ of a patient. The expanded assembly defines an inner volume and includes (i) a proximal base section configured to couple the assembly to the shaft's distal-end, (ii) a plurality of functional electrodes that are at least partially external to the inner volume and configured to be placed in contact with wall tissue of the cavity, and (iii) a reference ring electrode located on the proximal base section of the assembly externally to the inner volume, wherein the reference ring electrode is selectively positioned outside of the inner volume at the base section, and wherein the reference ring electrode is configured to be coupled with each of the plurality of functional electrodes for generating an electric field between each of the plurality of functional electrodes and the ring electrode.