Segmented Self-Expanding Stent for Aortic Dissection
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Solution Overview
Problem
Current treatments for type A aortic dissections require extensive and invasive surgeries, whereas existing self-expanding stents are not suitable for this condition, particularly due to their inability to effectively address the unique anatomical and physiological challenges of the ascending aorta.
Innovation Solution
A self-expanding nitinol stent with a closed-cell structure at its ends and an open-cell structure in the middle section, designed to expand under body heat, allowing for endovascular deployment through the iliac artery, expanding the true flow channel while closing the false channel, thus reducing the need for extensive surgery and ensuring flexibility to accommodate aortic growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a closed-cell structure is used throughout the stent, then fixation strength is improved, but flexibility deteriorates
Solution Approach 1:
The stent is divided into three distinct sections with different cell structures: closed-cell sections at the ends for fixation and an open-cell section in the middle for flexibility. This segmentation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different sections of the stent have different structural qualities tailored to their specific requirements. The closed-cell sections provide maximum structural integrity and fixation at the ends, while the open-cell section provides maximum flexibility and expandability in the central region where it needs to accommodate aortic growth.
2Productivity
If a self-expanding stent is used, then procedure time is reduced, but control over expansion precision deteriorates
Solution Approach 1:
The stent utilizes shape memory alloy properties where the material's physical state changes with temperature. The stent is deployed in a compressed state and automatically expands to its predetermined diameter when exposed to body temperature, eliminating the need for external expansion devices and providing precise, controlled expansion.
Solution Approach 2:
The stent performs its own expansion function using the body's thermal energy. The shape memory alloy material automatically transitions from a compressed low-temperature state to an expanded high-temperature state when placed in the body, eliminating the need for external balloons or mechanical expansion systems.
3Stability of the object's composition
If the stent is made entirely of closed-cell structure, then structural integrity is improved, but adaptability to aortic growth deteriorates
Solution Approach 1:
The stent is segmented into closed-cell sections for structural integrity at the ends and an open-cell section for adaptability in the middle. This allows the stent to maintain its shape where needed while accommodating aortic expansion and growth in the central region.
Solution Approach 2:
The open-cell section provides dynamic adaptability to aortic growth and expansion, while the closed-cell sections provide static structural integrity. The stent can therefore respond to physiological changes in the aorta while maintaining overall stability and fixation.
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 stent effectively expands the true flow channel and closes the false channel, reducing surgical invasiveness, shortening procedure time, and ensuring aortic structure preservation, making it safer and more efficient than traditional methods.
Implementation Method 1
Nitinol is an alloy of nickel and titanium and its characteristic ability is shape memory. This allows the product to be firmly packed into a narrow insertion system into the patient's body allowing it to reach the desired release site through the blood vessels. After being released by body heat, the stent recovers its original shape.
Data Source
Figure 1~2
AI summary
Self-expanding stent characterized in that has a closed-cell structure at its ends and it has an open-cell structure in the middle section; in the closed-cell section all stent meshes of the stent are connected to adjacent ones, while in the open-cell section only some meshes are connected to adjacent ones; the open-cell section is created by connecting the V-shaped elements to make a circle in the shape of a crown, and then the individual circles forming the length are connected by every fourth corner to the corner of the preceding circle, unlike the closed-cell section, where the circles forming the length are connected to all previous corners; in addition, the device at both ends in the closed-cell section expands to increase its diameter with respect to the central open-cell section.