Balloon Catheter Asymmetric Cooling Element
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Solution Overview
Problem
Existing balloon catheters for cryotherapy suffer from uneven cooling due to the thermal resistance of the fluid inside the balloon, leading to inadequate cooling of the balloon's surface and surrounding tissue, particularly in small diameter arteries.
Innovation Solution
The catheter design positions the elongate cooling element centrally within the balloon, with the guide wire lumen parallel and radially offset, allowing for uniform cooling across the balloon's surface and maintaining a small cross-sectional area, enabling efficient phase change cooling without the need for additional insulation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a co-axial cooling element design is used, then the catheter can maintain a small cross-sectional area suitable for small diameter arteries, but uneven cooling occurs due to thermal resistance of the fluid inside the balloon
Solution Approach 1:
The patent applies asymmetry by radially offsetting the cooling element from the central axis of the balloon. The cooling element is positioned at a distance of 0.1 to 0.5 mm from the central axis, creating an asymmetric configuration that allows the cold fluid to reach the balloon wall more effectively at the offset side, compensating for thermal resistance and achieving more uniform cooling across the balloon surface while maintaining a compact cross-sectional area.
2Temperature
If insulation layers are added to improve cooling uniformity, then temperature distribution improves, but the catheter diameter increases
Solution Approach 1:
Instead of adding insulation layers in the radial dimension which would increase catheter diameter, the patent solves the cooling uniformity problem by changing the spatial arrangement in another dimension - specifically by radially offsetting the cooling element from the central axis. This dimensional repositioning allows the cold fluid to more effectively reach the balloon wall, achieving uniform cooling without increasing the overall catheter diameter.
3Device complexity
If the cooling element is positioned centrally, then the design is simple, but spatial variations in heat transfer cause inadequate cooling of the balloon surface
Solution Approach 1:
The patent deliberately introduces asymmetry by offsetting the cooling element from the central axis of the balloon. This asymmetric positioning, with the cooling element located 0.1 to 0.5 mm from the central axis, creates a more efficient heat transfer path to the balloon wall, eliminating spatial variations in cooling while maintaining design simplicity. The offset position allows the cold fluid to directly contact the balloon wall more effectively.
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 design ensures improved cryotherapy by reducing spatial variations in heat transfer, making it suitable for applications in coronary vascular diseases and other procedures like atrial fibrillation, with the ability to maintain a small diameter for navigating small arteries and preventing coolant leakage.
Implementation Method 1
When exiting the supply lumen the coolant undergoes a phase change due to the pressure drop which occurs, causing it to evaporate and reduce in temperature
Implementation Method 2
When exiting the supply lumen the coolant undergoes a phase change due to the pressure drop which occurs, causing it to evaporate and reduce in temperature
Implementation Method 3
When exiting the supply lumen the coolant undergoes a phase change due to the pressure drop which occurs
Implementation Method 4
an elongate cooling element arranged to cool said inflation fluid for inflating the balloon
Data Source
AI summary
A catheter is provided comprising a flexible heat transfer element provided on an outer surface of the catheter, a conduit arranged to supply an inflation fluid for inflating the flexible heat transfer element so as to form an inflated balloon, a guide wire lumen for receiving a guide wire, and an elongate cooling element arranged to cool said inflation fluid for inflating the balloon. Said cooling element and said guide wire lumen are arranged inside the flexible heat transfer element such that, when inflated the cooling element is substantially central within the balloon and said guide wire lumen is parallel to and radially offset from the cooling element.