Cryotherapy Catheter with Nested Cooling Element
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Solution Overview
Problem
Conventional cryotherapy catheters face safety limitations, such as gas leakage risks and bulkier designs due to double balloon structures, making them unsuitable for small diameter arteries and ineffective for treating unstable or ruptured plaque.
Innovation Solution
A catheter design featuring a coaxial arrangement of tubes with a flexible heat transfer element and separate coolant and inflation fluid pathways, allowing for efficient cooling and reduced risk of gas leakage, suitable for small diameter arteries and effective in stabilizing unstable plaque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a double balloon structure is used to place insulation between balloons, then the target temperature can be achieved, but the bulk and diameter increase making the catheter difficult to manoeuvre in small diameter arteries
Solution Approach 1:
The catheter is divided into functionally independent components: a single balloon for insulation and temperature control, and a separate cooling element with internal coolant channels. This segmentation allows each component to be optimized independently - the balloon for thermal insulation and the cooling element for efficient heat transfer - while maintaining a compact overall structure that is easy to manoeuvre.
Solution Approach 2:
The cooling element is positioned within the balloon structure, creating a nested configuration. The cooling element contains internal channels that are surrounded by the balloon, allowing the cooling function to be integrated within the existing structural envelope. This nesting arrangement maximizes space utilization and maintains a compact diameter suitable for small arteries.
2Ease of manufacture
If a phase change Joule Thomson refrigerant system is used to inflate the catheter balloon, then the balloon can be inflated, but gas leakage causes serious harm or death due to emboli
Solution Approach 1:
The harmful phase change refrigerant system is extracted and replaced with a safe liquid inflation system. The catheter uses a liquid inflation fluid that can be safely contained and controlled, eliminating the gas leakage and emboli risks associated with phase change refrigerants. The cooling function is maintained through separate coolant channels that do not require phase change for inflation.
Solution Approach 2:
A liquid inflation fluid serves as an intermediary medium to inflate the balloon, replacing the problematic phase change refrigerant. This liquid intermediary provides reliable inflation without the safety hazards of gas-phase refrigerants, while the cooling function is achieved through a separate coolant circulation system that does not depend on phase change.
3Force
If conventional cryotherapy is used to treat calcified highly stenosed vessels, then the vessels can be forced open, but the temperatures used are warmer than those used in ablation fields
Solution Approach 1:
The catheter applies different temperature characteristics to different functional zones: the balloon provides warm pressure for vessel opening, while the cooling element provides localized cold for plaque stabilization. This local quality differentiation allows the system to achieve both mechanical dilation and thermal treatment effects simultaneously at the same site.
Solution Approach 2:
The catheter merges two previously separate functions - mechanical dilation and cryotherapy - into a single integrated device. The balloon and cooling element work together in the same catheter assembly, allowing simultaneous application of pressure for vessel opening and cold for plaque stabilization, thereby combining beneficial effects while eliminating the need for separate procedures.
4Stability of the object's composition
If cryotherapy is used to treat vulnerable or unstable plaque, then the plaque morphology can be changed, but the mechanism was previously poorly understood and improperly described
Solution Approach 1:
The system incorporates temperature sensing and monitoring capabilities that provide feedback on the cooling process. This feedback allows real-time adjustment of cooling parameters to achieve optimal plaque stabilization without excessive cooling. The feedback mechanism also enables precise control over the thermal field to ensure safe and effective treatment.
Solution Approach 2:
The catheter enables precise control over cooling parameters including temperature, duration, and spatial distribution. By allowing dynamic adjustment of these parameters, the system can adapt to different plaque types and locations, optimizing the transformation from unstable to stable plaque morphology while minimizing risks associated with improper cooling.
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 catheter effectively cools unstable plaque, changing its morphology to a stable state, reducing thrombus risk and facilitating healing, while being more maneuverable and safer than traditional designs.
Implementation Method 1
the inflation fluid provides a thermal pathway to conduct heat between a surface of the expandable membrane and the cooling chamber
Implementation Method 2
a phase change Joule Thomson refrigerant system in which liquid refrigerant transforms into a gas which inflates the catheter balloon
Implementation Method 3
a phase change Joule Thomson refrigerant system
Data Source
AI summary
Disclosed herein is a catheter for plaque stabilisation by cryotherapy, the catheter comprising: a first tube with a first end for receiving a flow of a coolant and a second end for supplying the flow of the coolant to a cooling element; a second tube, with a first end and a second end, wherein the second end of the second tube is configured to receive a flow of the coolant from the cooling element such that the second tube provides a flow path of the coolant from the second end of the second tube to the first end of the second tube; an inflatable flexible heat transfer element on the outer surface of the catheter; and a conduit for supplying an inflation fluid for inflating the flexible heat transfer element, wherein, when the flexible heat transfer element is inflated by the inflation fluid, the cooling element is configured to be within the balloon and in thermal conductivity with the inflation fluid; wherein the cooling element comprises an elongate tubular wall defining an elongate cooling chamber therein, the cooling chamber has a first end that is in fluid communication with the second end of the second tube and the cooling chamber has a second end that is closed.