Helical Bipolar Electrode for Transmural Ablation
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Solution Overview
Problem
Current ablation techniques for treating atrial fibrillation, such as the Maze procedure, are invasive and cause trauma, and existing electrodes used in less invasive methods often result in high tissue desiccation and resistance due to high current density and heat coagulation.
Innovation Solution
The use of low-pitch, helical or coil electrodes with a large surface area and a thermally conductive mass or slug, connected to a bipolar RF generator, to create transmural ablation lines with minimized current density and heat coagulation, allowing for minimally invasive procedures with reduced trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If linear or high-pitch threaded electrodes are used, then the electrode can be inserted into heart tissue, but high current density occurs causing tissue desiccation and high resistance
Solution Approach 1:
The patent combines multiple electrode segments (first electrode portion, second electrode portion, and optional third electrode portion) into a single integrated electrode structure. This merging creates a distributed current delivery system along the electrode length, reducing current density at any single point while maintaining effective tissue contact and insertion capability
Solution Approach 2:
The patent transitions from traditional linear or high-pitch threaded electrode designs to a low-pitch helical configuration. This dimensional change in electrode geometry increases the surface area in contact with tissue, distributing current more evenly and reducing current density without compromising insertion ability
2Reliability
If traditional electrodes are used, then ablation can be performed, but heat coagulation and trauma occur
Solution Approach 1:
The patent changes key parameters of the electrode design, specifically the pitch of the helical configuration and the distribution of conductive material along the electrode length. These parameter changes result in lower current density and more uniform heat distribution, achieving reliable ablation while minimizing excessive heat coagulation and tissue trauma
Solution Approach 2:
The patent creates different zones along the electrode with varying properties - the low-pitch helical sections provide current delivery with reduced local current density, while the optional thermally conductive mass at the distal end provides localized heat management. This local quality variation allows effective ablation with reduced harmful heat effects
3Object-affected harmful factors
If low-pitch helical electrodes with large surface area are used, then current density is reduced, but electrode complexity increases
Solution Approach 1:
The patent replaces complex multi-component electrode assemblies with a single integrated low-pitch helical electrode structure that can be inserted as one piece. This substitution maintains the current density reduction benefits while simplifying the overall device architecture and insertion procedure
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 enables the formation of effective ablation lines with reduced tissue coagulation and trauma, facilitating a less invasive approach to treating atrial fibrillation by minimizing current density and heat buildup, while allowing for precise placement and reduced recovery time.
Implementation Method 1
When the generator is activated, bipolar RF energy flows between the electrodes through the tissue, forming a transmural (through the heart wall) ablation line extending through the thickness of the heart tissue and between the electrodes
Implementation Method 2
the electrode or the distal end of the electrode is preferably fashioned to provide a large electrode surface area to provide relatively low current density in the vicinity of the electrode, thereby reducing the tissue desiccation and resultant high resistance that can occur in proximity to the electrode
Data Source
AI summary
A method and apparatus for creating transmural ablations in heart tissue, for example, may include two or more electrodes adapted to be connected to opposite poles of a bipolar RF generator so as to energize the electrodes to ablate cardiac tissue between the electrodes. A first electrode may be inserted into cardiac tissue at a first location and a second electrode may be inserted into cardiac tissue at a second location which is spaced from the first location. At least one of the electrodes may be adapted to provide a sufficiently low current density in the vicinity of the electrode to avoid substantial tissue desiccation when energized. Alternatively, the apparatus may include at least one bipolar ablation electrode which comprises an elongated conductive member of spiral shape having a pitch sufficiently small to provide sufficient surface area to avoid substantial desiccation of tissue when energized by a bipolar RF generator.