Expandable Mapping Catheter With Internal Reference ECG Electrode
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Solution Overview
Problem
Existing electrophysiological procedures face inaccuracies and instabilities in sensing unipolar electrocardiogram (ECG) signals due to noise introduced by external reference electrodes, leading to incorrect calculation of local activation times (LATs) and erroneous annotations of arrhythmias.
Innovation Solution
A catheter with an expandable distal-end assembly featuring ECG electrodes in contact with tissue and a central reference electrode within the assembly, maintaining a predefined distance from the electrodes and tissue, is used to sense unipolar ECG signals, which are processed to calculate accurate LATs and display annotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If external reference electrodes are used for sensing unipolar ECG signals, then the sensing setup is simple, but noise is introduced leading to inaccuracies in LAT calculation and annotation errors
Solution Approach 1:
A conductive fluid intermediary is introduced between the external reference electrode and the tissue to improve electrical contact and reduce noise. The conductive fluid acts as a mediator that enhances the quality of the reference signal without requiring direct tissue contact, thereby resolving the contradiction between simple setup and accurate measurement
Solution Approach 2:
The system uses the patient's own body fluids (blood, interstitial fluid) as a natural conductive medium by placing the reference electrode in direct contact with tissue or using endocardial contact. This self-service approach eliminates the need for external conductive gels or fluids while providing a stable, low-noise reference signal
2Object-affected harmful factors
If external reference electrodes are placed on the body surface, then the setup is non-invasive, but signal noise and instability increase
Solution Approach 1:
A conductive fluid intermediary is introduced between the external reference electrode and the tissue to improve electrical contact and reduce noise. The conductive fluid acts as a mediator that enhances the quality of the reference signal without requiring direct tissue contact, thereby resolving the contradiction between simple setup and accurate measurement
Solution Approach 2:
The system uses the patient's own body fluids (blood, interstitial fluid) as a natural conductive medium by placing the reference electrode in direct contact with tissue or using endocardial contact. This self-service approach eliminates the need for external conductive gels or fluids while providing a stable, low-noise reference signal
3Measurement precision
If reference electrode is placed in direct contact with tissue, then signal quality improves, but the risk of tissue damage and infection increases
Solution Approach 1:
A conductive fluid intermediary is introduced between the external reference electrode and the tissue to improve electrical contact and reduce noise. The conductive fluid acts as a mediator that enhances the quality of the reference signal without requiring direct tissue contact, thereby resolving the contradiction between simple setup and accurate measurement
Solution Approach 2:
The system uses the patient's own body fluids (blood, interstitial fluid) as a natural conductive medium by placing the reference electrode in direct contact with tissue or using endocardial contact. This self-service approach eliminates the need for external conductive gels or fluids while providing a stable, low-noise reference signal
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
Improves the quality of unipolar ECG signal sensing and annotation accuracy, enhancing electro-anatomical mapping and ablation procedure success rates by reducing noise and instability.
Implementation Method 1
a reference electrode, which is positioned within an inner volume of the distal-end assembly, and in an expanded position of the distal-end assembly, the reference electrode: (i) has no physical contact with the tissue, and (ii) is positioned at a first distance from the first ECG electrode and at a second distance from the second ECG electrode, and a difference between the first and second distances is smaller than a predefined threshold
Data Source
AI summary
A catheter includes: (a) a shaft for insertion into a heart of a patient, (b) an expandable distal-end assembly, which is coupled to the shaft and is configured to make contact with tissue of the heart, (c) at least first and second electrocardiogram (ECG) electrodes, which are coupled to an outer surface of the expandable distal-end assembly, and when placed in contact with the tissue, are configured to sense ECG signals in the tissue, and (d) a reference electrode, which is positioned within an inner volume of the distal-end assembly, and in an expanded position of the distal-end assembly, the reference electrode: (i) has no physical contact with the tissue, and (ii) is positioned at a first distance from the first ECG electrode and at a second distance from the second ECG electrode, and the difference between the first and second distances is smaller than a predefined threshold.