Electrode-Tissue Coupling Index via Complex Impedance
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Solution Overview
Problem
Current methods for assessing the degree of coupling between medical device electrodes and tissue, such as cardiac tissue, are inadequate due to reliance on clinician experience, radiation exposure, time-consuming procedures, and high rates of false positives/negatives, failing to provide a direct measure of electrical coupling and tissue contact.
Innovation Solution
A system and method using an electronic control unit to acquire and calculate a coupling index based on complex impedance components like resistance and reactance between the electrode and tissue, providing a clear indication of the degree of coupling for improved assessment and interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluoroscopic imaging is used to assess electrode-tissue contact, then visual confirmation of catheter position is achieved, but radiation exposure to patient and clinician increases and quantification of contact degree remains difficult
Solution Approach 1:
The patent replaces fluoroscopic imaging (optical/radiation-based system) with an electrical impedance measurement system. The impedance sensor detects electrical properties at the electrode-tissue interface, providing contact assessment without radiation exposure. This substitution maintains measurement capability while eliminating the harmful radiation effect.
Solution Approach 2:
The patent introduces electrical impedance as an intermediary parameter to assess electrode-tissue contact. Instead of directly imaging the contact (fluoroscopy), the system measures electrical impedance changes that occur when the electrode contacts tissue, providing indirect but accurate contact detection without radiation.
2Measurement precision
If intracardiac echo is used to assess tissue contact, then real-time imaging is provided, but the procedure becomes time-consuming and alignment with the ablation catheter is difficult
Solution Approach 1:
The patent replaces intracardiac echo (acoustic imaging system) with electrical impedance measurement. This substitution eliminates the time-consuming aspects of echo acquisition and processing while providing continuous, real-time contact feedback through simple electrical measurements that can be taken instantaneously.
Solution Approach 2:
The impedance sensor provides self-contained contact detection capability at the catheter tip, eliminating the need for separate echo imaging procedures and complex alignment processes. The system uses the electrode itself as both the therapeutic tool and the sensing element, providing contact information directly at the treatment site without requiring external imaging systems.
3Ease of operation
If clinician sense based on tactile feedback is used to evaluate contact, then subjective assessment is obtained, but reliability varies based on clinician experience and catheter mechanical properties
Solution Approach 1:
The patent implements objective electrical impedance feedback to supplement or replace subjective tactile feedback. The impedance measurement provides quantifiable, consistent data about electrode-tissue contact that is independent of clinician experience or catheter mechanical variations, while maintaining ease of operation through automated measurement and display.
Solution Approach 2:
The patent replaces the mechanical tactile feedback system (relying on clinician sense and catheter mechanical properties) with an electrical measurement system. This substitution provides objective, reproducible contact assessment that does not vary with clinician experience or catheter design differences, while keeping the operation simple through automated sensing.
4Device complexity
If simple impedance measurement is used to assess coupling, then measurement is simplified, but the complex nature of tissue impedance requires interpretation of multiple components for accurate coupling assessment
Solution Approach 1:
The patent segments the complex tissue impedance into distinct components (resistive and reactive) that can be measured and analyzed separately. This segmentation allows the system to capture different aspects of the electrode-tissue interface physics while maintaining a relatively simple overall measurement approach. The separate components provide more nuanced information about coupling quality.
Solution Approach 2:
The patent measures impedance at multiple frequencies or analyzes different impedance parameters (magnitude, phase, real and imaginary components) to accurately assess coupling. By changing the measurement parameters rather than simplifying them, the system maintains measurement simplicity while extracting comprehensive information about electrode-tissue coupling quality.
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 offers a more accurate and efficient assessment of electrode-tissue coupling, enhancing the safety and effectiveness of medical procedures by providing a direct measure of energy delivery and tissue contact, reducing complications and improving procedural success rates.
Implementation Method 1
an electronic control unit to acquire values for first and second components of a complex impedance between the electrode and the tissue
Data Source
AI summary
A system and method for assessing a degree of coupling between an electrode and tissue in a body is provided. Values for first and second components of a complex impedance (e.g., resistance and reactance or impedance magnitude and phase angle) between the electrode and the tissue are obtained. From these values, a coupling index is calculated that is indicative of a degree of coupling between the electrode and the tissue. The coupling index may be displayed to a clinician in a variety of ways to indicate the degree of coupling to the clinician. The system and method find particular application in ablation of tissue by permitting a clinician to create lesions in the tissue more effectively and safely.