Two-Stage RF Ablation Method for Deep Tissue Lesions
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Solution Overview
Problem
Current radiofrequency (RF) ablation technologies face challenges in achieving adequate depth and minimizing tissue volume, particularly in thick biological tissues, due to shallow heat penetration and non-uniform heating, often resulting in excessive tissue damage.
Innovation Solution
A two-stage RF ablation method using bipolar or unipolar energy delivery between distinct electrode pairs, where the first stage forms opposing ablation regions and the second stage completes the ablation through the tissue depth using a diametrical electrode arrangement, reducing power and time in the first stage to minimize tissue volume and ensuring complete ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If RF ablation is performed with high power to achieve adequate depth, then ablation depth is improved, but tissue volume increases and overheating occurs
Solution Approach 1:
The ablation process is divided into two distinct stages: a first stage using opposing electrode pairs to create initial ablation regions, and a second stage using diametrical electrode pairs to complete the ablation through the tissue. This segmentation allows lower power to be used in the first stage (reducing volume) while achieving complete depth in the second stage.
Solution Approach 2:
The first stage of ablation creates preliminary ablation regions that reduce the remaining tissue thickness and modify the electrical pathways. This preliminary action enables the second stage to complete the ablation more efficiently with controlled energy delivery, avoiding excessive heating and volume loss.
2Length of stationary object
If RF ablation is performed to ablate through thick tissue, then ablation depth is improved, but non-uniform heating and overheating occur
Solution Approach 1:
By dividing the ablation into two stages with different electrode configurations, the thermal load is distributed over time. The first stage creates initial lesions with controlled heating, and the second stage completes the ablation with modified thermal parameters, preventing runaway heating and ensuring uniform temperature distribution throughout the tissue depth.
3Ease of operation
If single-stage ablation is used to simplify the procedure, then ease of operation is improved, but ablation depth and tissue volume control are compromised
Solution Approach 1:
The two-stage approach, while more complex than single-stage ablation, provides precise control over ablation depth and volume. The first stage establishes initial regions with controlled parameters, and the second stage completes the procedure with optimized settings, achieving superior depth and volume control that justifies the additional procedural step.
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 increases the depth of ablation lesions while reducing the overall volume of ablated tissue, avoiding overheating and minimizing unnecessary tissue damage.
Implementation Method 1
RF ablation may generate significant heat, which if not controlled can result, generally, in undesired or excessive tissue damage. Most of the Ohmic heat is generated near the RF electrodes
Implementation Method 2
The cross-sectional profile (i.e., depth) of ablation is often too shallow, in part because most of the Ohmic heat is generated near the RF electrodes
Implementation Method 3
the rate at which heat diffuses deep into the tissue layer(s) is extremely slow
Implementation Method 4
the rate at which heat diffuses deep into the tissue layer(s) is extremely slow, and may be counteracted by the cooling effects due to blood perfusion
Data Source
AI summary
A method of ablating a tissue site includes at least two stages. A first stage involves conducting bipolar ablation between a first pair of electrodes situated in an opposing arrangement on opposing sides of the tissue site to form a pair of opposing first stage ablation regions extending from respective sides of the tissue towards the center. A second stage involves conducting bipolar ablation between a second pair of electrodes situated in a diametrical arrangement with respect to the first stage ablation regions, which forms a second stage ablation region intermediate the pair of first stage ablation regions. The second stage completes the ablation through the entire depth of the tissue site. Since the overall process can accommodate incomplete ablation during the first stage, lower power, reduced ablation times or both may be used during the first stage, avoiding overheating and with a decrease in ablated tissue volume.