Lesion Size Estimation Using Non-Linear Force Power Integration
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Solution Overview
Problem
Existing methods for estimating the size of lesions created during cardiac tissue ablation using radiofrequency energy are inexact, as they assume a linear relationship between force, power, and time, which is highly non-linear in reality.
Innovation Solution
A method involving the measurement of contact force and power during ablation, with the cessation of the procedure when a desired lesion size is reached, estimated using an integral of the product of contact force raised to a non-unity exponent and power raised to another non-unity exponent, providing more accurate estimates of lesion volume, depth, or diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear relationship between force, power, and time is assumed for lesion size estimation, then the estimation model is simple, but the accuracy of lesion size estimation deteriorates
Solution Approach 1:
The patent changes the parameters of the estimation model by introducing non-unity exponents (α and β) for force and power respectively, transforming the linear relationship into a non-linear power law relationship. This allows the model to capture the actual non-linear behavior of lesion formation while maintaining a relatively simple mathematical structure.
Solution Approach 2:
The patent makes the estimation model dynamic by allowing the exponents α and β to be determined from experimental data rather than being fixed. This enables the model to adapt to different tissue types and ablation conditions, improving accuracy without requiring complex real-time calculations.
2Measurement precision
If non-unity exponents are used in the lesion size estimation equation, then the accuracy of lesion size estimation is improved, but the complexity of the estimation model increases
Solution Approach 1:
The patent modifies the parameters of the estimation equation by introducing non-unity exponents α and β. These parameters are determined through experimental data analysis and can be pre-calculated for different tissue types, avoiding the need for complex real-time computations while maintaining high accuracy.
3Manufacturing precision
If ablation continues until a desired lesion size is reached using non-unity exponents, then the precision of lesion size control is improved, but the time required for ablation increases
Solution Approach 1:
The patent implements a feedback control mechanism where the ablation process is monitored continuously and terminated when the estimated lesion size reaches the desired threshold. This feedback approach ensures precise lesion size control while minimizing unnecessary ablation time by stopping the procedure as soon as the target is achieved.
Solution Approach 2:
The patent performs preliminary calculations of the integral term before the ablation procedure to determine the desired ablation time. This allows the operator to plan the ablation duration in advance based on tissue characteristics and desired lesion size, reducing overall procedure time while maintaining precision.
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 results in more precise control over lesion size, with equations (2), (3), and (4) providing good estimates of lesion size, as validated by experimental data and regression analysis, improving the accuracy of ablation procedures.
Implementation Method 1
electromagnetic radiofrequency (RF) energy is injected from a catheter electrode into the tissue, causing ablation and production of a lesion
Implementation Method 2
electromagnetic radiofrequency (RF) energy is injected from a catheter electrode into the tissue, causing ablation
Implementation Method 3
measuring a contact force applied during the time period
Data Source
AI summary
A method, consisting of ablating tissue for a time period, measuring a contact force applied during the time period, and measuring a power used during the time period. The method further includes ceasing ablating the tissue when a desired size of a lesion produced in the tissue, as estimated using an integral over the time period of a product of the contact force raised to a first non-unity exponent and the power raised to a second non-unity exponent, is reached.