Frozen Matrix Loading for Self-Expanding Stents
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Solution Overview
Problem
Existing methods for loading self-expanding stents into deployment catheters are inefficient and prone to damage due to the stents' fragility and small size, making longitudinal movement and radial constraint management challenging, especially for long stents.
Innovation Solution
The method involves applying a frozen support matrix to the stent by cooling it and applying a fluid that freezes to form a solid plug, allowing the stent to be compressed and loaded into the catheter lumen, with the matrix subsequently sublimating to leave the stent in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-expanding stents are loaded into deployment catheters using conventional methods (push loading or inch-worm loading), then the stents can be inserted into the catheter lumen, but the stents are prone to damage due to their fragility and difficulty in handling
Solution Approach 1:
A frozen matrix acts as an intermediary substance that temporarily supports the fragile stent during loading operations. The matrix is applied in frozen state to provide rigid support, enabling safe manipulation and insertion into the catheter lumen. After loading, the matrix sublimates away, leaving the stent intact and properly positioned.
Solution Approach 2:
The physical state of the support matrix is changed from solid (frozen) to gas (sublimated) to provide temporary support during loading. By controlling temperature and pressure parameters, the matrix provides structural support when frozen and then disappears through sublimation after serving its protective function.
2Length of moving object
If long self-expanding stents (equal to or greater than 100 mm) are loaded into deployment catheters, then complete stent loading is achieved, but the difficulty of handling and moving increases significantly
Solution Approach 1:
The frozen matrix serves as a mediator that provides distributed support along the entire length of long stents, enabling uniform handling and movement. The matrix-stent combination can be manipulated as a single unit, overcoming the flexibility and handling difficulties inherent to long, fragile stent structures.
3Shape
If the stent diameter is reduced for loading into the catheter lumen, then the stent can be inserted, but the stent becomes more vulnerable to damage
Solution Approach 1:
The frozen matrix provides beforehand cushioning and protection to the stent during the diameter reduction and loading process. The matrix absorbs mechanical stresses and prevents direct contact forces from damaging the crimped stent structure, enabling safe diameter reduction and insertion.
Solution Approach 2:
The frozen matrix acts as a protective intermediary between external loading forces and the stent structure. During crimping and insertion, the matrix distributes and cushions forces, preventing stress concentrations that could damage the already compromised stent structure.
4Device complexity
If conventional loading methods are used without support structures, then the loading process is simpler, but the accuracy and reliability of stent placement decreases
Solution Approach 1:
The frozen matrix provides a stable intermediary platform that enables precise positioning and control of the stent during loading. The matrix allows for accurate alignment and insertion into the catheter lumen, improving placement precision despite adding process complexity.
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 enables reliable, efficient, and damage-free loading of long self-expanding stents into catheters, facilitating precise placement without causing structural damage, and allows for higher axial push-loading forces with minimal loading failures.
Implementation Method 1
cooling the article to a predetermined temperature
Implementation Method 2
applying a fluid to the article, the fluid freezing at or below the predetermined temperature
Implementation Method 3
removing the matrix from the inserted stent by sublimation
Data Source
AI summary
A method of loading an article, such as a self-expanding stent, into a structure, such as a delivery catheter, including the steps of chilling the article to a predetermined temperature, reducing article size a predetermined amount, inserting fluid into the article, whereby the fluid forms a substantially solid plug with respect to the article, and moving the frozen article. Also provided is an apparatus for loading an article into a structure including: an article size reduction element, a chiller connected to the size reduction element, a cold source communicatively connected to the chiller, and a fluid supply communicatively connected to the size reduction element.