Dual-Sheath Stent Delivery for Precise Low-Friction Deployment
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Solution Overview
Problem
Existing stent deployment systems face challenges with inaccurate stent placement due to high frictional forces between the stent and sheath during retraction, particularly in self-expanding stents, which can lead to damage and suboptimal deployment.
Innovation Solution
A stent delivery system utilizing two sliding surfaces, with a reduced area between the stent and outer sheath, and a second surface optimized with a solid lubricant, such as graphene, to minimize frictional forces, allowing independent retraction of inner and outer sheaths for precise stent deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sheath is used to cover the stent, then the device structure is simple, but it is difficult to control the expansion timing and position of the stent
Solution Approach 1:
The single sheath is divided into two separate sheaths: an inner sheath and an outer sheath. The inner sheath covers the proximal portion of the stent while the outer sheath covers the distal portion. This segmentation allows independent control of each sheath's retraction, enabling precise control over when and where the stent expands during deployment.
2Reliability
If the delivery system is designed for precise stent deployment, then deployment control is improved, but the procedure time increases
Solution Approach 1:
The two sheaths are pre-positioned on the catheter shaft before reaching the target site, with the inner sheath already in place over the proximal stent portion and the outer sheath over the distal portion. This preliminary arrangement eliminates the need for complex positioning maneuvers during the procedure, allowing rapid and accurate deployment when the sheaths are retracted.
3Ease of operation
If lubricant is applied to reduce friction during sheath retraction, then retraction smoothness is improved, but lubricant residue may contaminate the stent
Solution Approach 1:
A lubricant is introduced as an intermediary substance between the sheath surfaces to reduce friction during retraction. The lubricant is applied in a controlled manner and is designed to be easily removed or to not adhere to the stent surface, thereby smoothing the retraction process while preventing contamination of the medical device.
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 reduces overall frictional forces, enabling accurate and controlled stent deployment with reduced shear stress, minimizing damage to coated stents and ensuring precise placement.
Implementation Method 1
a lubricant disposed between the inner sheath and the outer sheath
Implementation Method 2
self-expanding stent having a proximal end region, a distal end region, and a length extending therebetween
Data Source
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AI summary
The invention relates to A stent delivery system comprising an elongate catheter shaft having a distal end region and a proximal end region, a stent having a proximal end region, a distal end region, and a length extending therebetween, the stent disposed about the distal end region of the elongate catheter shaft, a handle including an actuation assembly, and a delivery sheath having a proximal end region and distal end region, the proximal end region affixed to a portion of the actuation assembly, wherein the delivery sheath is disposed over the elongate catheter shaft and the stent, the delivery sheath comprising: an outer sheath having a proximal end region and a distal end region; an inner sheath slidably disposed within the outer sheath, the inner sheath having a proximal end region and a distal end region, and a lubricant disposed between the inner sheath and the outer sheath, wherein the outer sheath is configured to be proximally retracted independently of the inner sheath over a distal portion of the stent and simultaneously with the inner sheath over a proximal portion of the stent.