Force-Time Integral Lesion Size Control in Ablation Catheters
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Solution Overview
Problem
Catheter-based contact ablation techniques for treating atrial fibrillation face challenges such as unpredictable lesion size, risk of steam popping, and limited visualization of ablation procedures, leading to variable effectiveness and potential complications.
Innovation Solution
The use of a force-time integration technique to predict and visualize lesion size, combined with real-time control of energy delivery based on contact force, to prevent steam popping and ensure accurate tissue ablation, along with comprehensive visualization of ablation outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If catheter-based contact ablation techniques are used to treat atrial fibrillation, then the need for open surgery is reduced and patient recovery time is shortened, but the lesion size becomes unpredictable and steam popping occurs
Solution Approach 1:
The system performs preliminary actions by measuring contact force before energy delivery and calculating the force-time integral in real-time. This allows prediction of lesion size before the ablation actually occurs, enabling operators to adjust parameters to achieve desired lesion characteristics while preventing steam popping.
Solution Approach 2:
The system implements continuous feedback by monitoring contact force during ablation, calculating the force-time integral, and using this information to predict lesion size. This feedback loop allows real-time adjustment of ablation parameters to maintain precise lesion size control and prevent complications.
2Reliability
If higher energy is delivered to ensure complete ablation, then electrical isolation is achieved, but the risk of steam popping and tissue damage increases
Solution Approach 1:
The system monitors contact force in real-time and uses the force-time integral to predict lesion size, providing feedback that allows adjustment of energy delivery parameters. This ensures sufficient energy is delivered for complete electrical isolation while preventing excessive energy that would cause steam popping.
Solution Approach 2:
The system changes ablation parameters based on measured contact force characteristics. By adjusting energy delivery according to the force-time integral, the system optimizes the balance between achieving complete ablation for electrical isolation and preventing harmful steam popping.
3Manufacturing precision
If real-time monitoring of contact force is implemented, then lesion size can be predicted and controlled, but the device complexity increases
Solution Approach 1:
The force sensing catheter integrates multiple functions into a single device: contact force measurement, lesion size prediction through force-time integral calculation, and guidance for energy delivery. This multi-functionality reduces the need for separate monitoring devices while providing comprehensive lesion control.
4Reliability
If the ablation procedure is extended to ensure complete coverage, then electrical isolation is achieved, but the procedure time and patient exposure to risks increase
Solution Approach 1:
The system performs preliminary calculation of the force-time integral before completing each ablation lesion, allowing prediction of whether the lesion achieves sufficient size for electrical isolation. This enables operators to efficiently plan the ablation strategy and avoid unnecessary extensions of the procedure while ensuring complete coverage.
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 allows for reliable prediction and visualization of lesion size and tissue damage, reducing the incidence of steam popping and improving procedural efficiency, ensuring effective electrical isolation while minimizing tissue damage and complications.
Implementation Method 1
a force sensor operatively coupled with the ablation head and adapted to detect a contact force exerted on the ablation head from contact with the target tissue, the force sensor outputting a signal in response to the contact force
Implementation Method 2
The ablation head is then energized for a period of time while the sequence of contact forces is being measured
Implementation Method 3
integrating the sequence of contact forces that were measured with the force sensor over the period of time of energizing the ablation head to determine a force-time integral
Implementation Method 4
predicting a size parameter of a lesion on the target tissue created by the energization parameter, the prediction being based on the force-time integral and the magnitude of current
Data Source
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AI summary
A method and apparatus that utilizes a force-time integral for real time estimation of lesion (46) size in catheter-based (32) ablation systems (30). The apparatus measures the force exerted by a contact ablation probe (36, 38) on a target tissue (40) and integrates the force over an energization time of the ablation probe. The force-time integral can be calculated and utilized to provide an estimated lesion (46) size (depth, volume and/or area) in real time. The force-ttme integral may also account for variations in the power (42) delivered to the target tissue (40) in real time to provide an improved estimation of the lesion (46) size. In one embodiment, the force metric can be used as feedback to establish a desired power level delivered to the probe (36, 38) to prevent steam popping.