Cryoablation Segment Uniform Lesion Cooling
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Solution Overview
Problem
Existing cryoablation techniques face challenges in uniformly maintaining cooling and warming rates along a linear tissue lesion, particularly in creating deep and long, uniform lesions for conditions like atrial fibrillation, where simultaneous ablation of targeted tissue is necessary while avoiding non-target tissue impact.
Innovation Solution
A fluid refrigerant delivery system for cryoablation applicators, including a cylindrical, flexible polymeric cryoablation segment with multiple exhaust ports, where the refrigerant is preconditioned to ensure uniform mass flow and phase change from liquid to gas along the segment, maintaining the refrigerant in a liquid state until it exits, thereby ensuring uniform cooling and preventing premature boiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a one-step cooling process is used to ablate a linear lesion, then productivity is improved, but manufacturing precision deteriorates because uniform cooling along the length of the contact surface becomes difficult to achieve
Solution Approach 1:
The contact surface is divided into multiple segments, each with its own refrigerant delivery system. This allows independent control of cooling in different zones along the linear contact surface, enabling uniform temperature distribution while maintaining one-step ablation capability.
Solution Approach 2:
Each segment of the contact surface is equipped with dedicated refrigerant delivery and temperature sensing systems. This provides localized control and monitoring of cooling conditions, ensuring uniform temperature distribution across the entire linear contact surface during one-step ablation.
2Use of energy by moving object
If phase change refrigerant is used to cool a relatively long linear contact surface, then cooling efficiency is improved, but device complexity increases because multiple vaporization points are required
Solution Approach 1:
The contact surface is divided into multiple segments, each with its own refrigerant delivery system. This segmentation allows distributed phase change vaporization points along the linear contact surface, improving cooling efficiency while managing device complexity through modular architecture.
Solution Approach 2:
A refrigerant control unit acts as an intermediary, regulating and distributing refrigerant to multiple vaporization points along the linear contact surface. This centralized control mechanism simplifies the overall system by coordinating multiple vaporization points through a single control interface.
3Speed
If the refrigerant is delivered at high pressure to ensure rapid phase change, then cooling rate is improved, but reliability deteriorates due to premature boiling before reaching the contact surface
Solution Approach 1:
The refrigerant delivery system provides localized control of refrigerant flow and pressure at each segment along the linear contact surface. This ensures that phase change occurs at the appropriate location and time, maintaining reliable and consistent cooling without premature boiling.
Solution Approach 2:
Temperature sensing systems at each segment provide feedback to the refrigerant control unit. This feedback mechanism allows real-time adjustment of refrigerant delivery parameters, ensuring phase change occurs at the optimal moment and location, thereby maintaining both high cooling rate and reliability.
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 system effectively creates uniform linear lesions by maintaining consistent cooling and warming rates, enhancing tissue destruction efficiency and ease of use while being cost-effective.
Implementation Method 1
phase change refrigerants can be used to cool a contact surface by undergoing a liquid to gas phase transition in close proximity to the contact surface
Implementation Method 2
it can become necessary to vaporize the liquid refrigerant at more than one point along the length of the contact surface
Implementation Method 3
the refrigerant is in a liquid state at a working pressure, that is in a range of approximately 350-500 psia, and it is at a pre-cooled working temperature of about minus forty degrees Centigrade
Data Source
AI summary
An applicator for cryoablating tissue to form linear (i.e. straight line and curvilinear) lesions in targeted tissue includes a fluid refrigerant delivery system having a source of a fluid refrigerant and a tubular cryoablation segment. Structurally, the segment has an open proximal end and a distal end, and is formed with a lumen. Also, the segment is formed with at least one distal port and at least one proximal port, with each port connected in fluid communication with the segment's lumen. The proximal end of the tubular segment is operably connected in fluid communication with the source of fluid refrigerant. For the system, the ports can be selectively sized to outflow liquid refrigerant through the distal and proximal ports at a substantially same mass flow rate.