Virtual-Electrode Catheter Cooled Fluid Ablation
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Solution Overview
Problem
Conventional RF ablation techniques for treating cardiac arrhythmias using virtual-electrode catheters are inefficient, with high power requirements leading to temperature increases and energy loss, resulting in only 2% of applied energy being used for lesion creation, while the remaining 98% is lost to heating other substances.
Innovation Solution
A virtual-electrode catheter design featuring a catheter body with an internal lumen for conductive fluid flow, an internal flexible conductor, and surface electrodes, which creates a concentrated electric field between the internal and surface electrodes to deliver ablative energy efficiently, allowing for deeper lesions with lower power and reduced fluid volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high power RF energy is delivered to achieve deeper ablation depth, then the ablation depth increases, but rapid temperature increases and hot-spots occur at the electrode-tissue interface
Solution Approach 1:
The patent introduces cooled conductive fluid as an intermediary substance between the RF electrode and tissue. The fluid flows through channels in the catheter body, absorbing excess heat from the electrode while conducting RF energy to the tissue, thereby preventing hot-spots at the electrode-tissue interface while enabling deeper ablation
Solution Approach 2:
The patent changes the physical parameters of the ablation system by introducing fluid flow rate and temperature as controllable variables. By adjusting fluid flow rate and temperature, the system can deliver sufficient RF energy for deep ablation while maintaining safe temperature levels at the electrode-tissue interface through active cooling
2Length of stationary object
If high power RF energy is delivered to increase ablation depth, then the ablation depth increases, but energy loss increases (only 2% of applied energy used for lesion creation)
Solution Approach 1:
The patent applies local quality by concentrating RF energy delivery at the specific site of interest through the cooled conductive fluid. The fluid acts as a medium that directs energy locally to the tissue interface where it is needed, reducing energy loss to surrounding substances and improving the efficiency of energy utilization for lesion creation
Solution Approach 2:
The cooled conductive fluid serves as an intermediary that efficiently transfers RF energy from the electrode to the tissue with minimal energy loss. The fluid's high thermal conductivity and continuous flow ensure that energy is delivered directly to the target tissue rather than being lost to heating the electrode or surrounding structures
3Length of stationary object
If high power RF energy is delivered to achieve deeper lesions, then the ablation depth increases, but the volume of fluid required increases (over 140 ml for full-circumferential lesion)
Solution Approach 1:
The patent optimizes the volume of conductive fluid required by controlling fluid flow rate parameters. By adjusting flow rate to match the specific energy delivery requirements of the ablation procedure, the system achieves deep lesions while minimizing fluid volume, avoiding unnecessary fluid administration and associated risks
4Ease of manufacture
If conventional unipolar mode is used with dispersive electrodes placed remotely, then the setup is simple, but RF energy decreases rapidly with distance (1/r4)
Solution Approach 1:
The patent segments the catheter structure into distinct functional components: an active RF electrode for energy delivery, cooled fluid channels for heat management, and surface electrodes for current return. This segmentation allows each component to be optimized independently, maintaining simple setup while improving RF energy delivery efficiency through the cooled fluid pathway
Solution Approach 2:
The cooled conductive fluid acts as an intermediary that bridges the gap between the active electrode and tissue, maintaining efficient RF energy delivery. The fluid pathway provides a controlled medium through which energy is transmitted to the tissue interface, overcoming the rapid energy decay with distance inherent in unipolar configurations
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 solution enhances the efficiency of RF ablation by localizing energy delivery, reducing power requirements, and minimizing fluid volume, thereby improving the effectiveness of lesion creation while minimizing energy wastage.
Implementation Method 1
The internal flexible conductor is adapted to deliver treatment energy to the tissue via the conductive fluid in the first internal lumen
Implementation Method 2
The virtual electrode technique mitigates this problem of temperature increases at the electrode-tissue interface by using cooled conductive fluid flowing onto the tissue surface
Implementation Method 3
upon activation of the source of ablative energy, an electric field is created between the active internal electrode and the at least one passive external electrode
Data Source
AI summary
Virtual-electrode catheters and methods for using such virtual-electrode catheters are disclosed. For example, bipolar and multipolar, virtual-electrode catheters having at least one internal electrode and at least one surface electrode, and methods of using these catheters for treatment of cardiac arrhythmias via, for example, radiofrequency (RF) ablation are disclosed. The catheters may comprise a catheter body with an internal lumen extending within it and adapted to flowingly receive a conductive fluid. An exit feature defining a flow path from the internal lumen to the catheter's outer surface may exist through a sidewall of the catheter body. A conductor is mounted within the internal lumen adjacent to the exit feature and is adapted to deliver treatment energy to the tissue via the conductive fluid in the internal lumen. At least one surface electrode is mounted on the outer surface of the catheter body adjacent to the exit feature.