Optic-Based Catheter Contact Sensing for Ablation
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Solution Overview
Problem
Current catheter systems face challenges in ensuring consistent mechanical contact between the electrode and tissue, particularly in dynamic environments like a beating heart, leading to potential false positives in contact detection and difficulties in directing irrigation during ablation procedures.
Innovation Solution
An optic-based catheter system with optical sensors that detect changes in reflected light energy, designed to be insensitive to RF fields and thermal effects, and equipped with a flexible coupling member to accurately measure contact force and orientation, minimizing false positives and ensuring effective irrigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If remotely placed sensors are used to detect contact, then the system can monitor contact parameters, but false positive outcomes occur when nonconductive catheter wall contacts tissue instead of electrode
Solution Approach 1:
The patent replaces mechanical contact sensing with optical sensing. An optical sensor detects contact by measuring changes in reflected light energy from the electrode surface, eliminating the need for mechanical pressure sensors that can be triggered by catheter wall contact. The optical sensor is positioned to detect light only from the electrode, not the catheter wall, thereby preventing false positives.
Solution Approach 2:
The patent introduces light as an intermediary medium between the electrode and the detection system. The optical sensor detects contact indirectly by measuring changes in reflected light energy, rather than directly sensing mechanical contact. This intermediary approach allows differentiation between electrode contact (which blocks light) and catheter wall contact (which does not affect light path).
2Reliability
If the electrode is placed in consistent mechanical contact with tissue, then effective treatment is achieved, but the dynamic movement of heart walls makes maintaining constant contact difficult
Solution Approach 1:
The patent implements a feedback system where the optical sensor continuously monitors electrode-tissue contact status by detecting changes in reflected light energy. This real-time feedback allows the system to detect loss of contact and alert the operator or automatically adjust the catheter position to maintain consistent electrode-tissue contact during heart wall movement.
Solution Approach 2:
The patent acknowledges the dynamic nature of the heart wall movement and uses dynamic optical sensing to track contact status. The optical sensor system can adapt to changing geometric relationships between electrode and tissue by continuously measuring reflected light energy, allowing the system to maintain reliable contact detection despite the dynamic environment.
3Reliability
If optical sensors are used to detect contact, then false positives are reduced, but the system becomes sensitive to RF fields and thermal effects during ablation
Solution Approach 1:
The patent applies local quality by positioning the optical sensor and light source in a specific geometric configuration where the light path is localized to the electrode surface only. The sensor is oriented to detect reflected light from the electrode at a specific angle, making the measurement localized and insensitive to distant RF fields or thermal effects from the ablation site.
Solution Approach 2:
The patent converts the potential harm of RF fields and thermal effects into a benefit by using the fact that these effects do not significantly alter optical properties in the sensor's measurement zone. The optical sensing operates in a different physical domain (optical rather than electromagnetic RF), allowing the ablation energy to proceed without interfering with contact detection, and the system can even use thermal expansion of materials as a secondary contact indicator.
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
The system provides accurate contact force measurement and orientation, reducing false positives and enhancing the precision and safety of ablation procedures by ensuring consistent electrode-tissue contact and directed irrigation.
Implementation Method 1
an optical sensor for detecting changes in reflected energy from an optically interactive surface provided by the electrode
Data Source
AI summary
A contact sensing assembly including a catheter and an electrode including a tip portion and a base portion, and a generally central axis, with the electrode being connected to a distal end of the catheter. Optical sensor(s) may be provided for emitting and/or receiving an optical signal, with a part of the optical signal being transverse to the central axis. Optical interference member(s) may be provided for interfering with the optical signal. A method for sensing contact force exerted by an electrode on a tissue includes directing an optical signal along a portion of a catheter, emitting and/or receiving an optical signal, with a part of the optical signal being at a predetermined angle relative to the central axis, and sensing changes in intensity of the optical signal based on displacement associated with the electrode tip portion based on the contact force exerted by the electrode on the tissue.