PTFE Sheath Split Design for Stent Delivery Friction
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Solution Overview
Problem
Endovascular devices, particularly covered stents, face significant challenges in delivery due to excessive friction with catheter walls, which limits their efficient deployment through tortuous anatomy, especially when they have a large surface area and need to be compressed into small catheters.
Innovation Solution
A delivery system that employs a PTFE sheath with a distal end split into two halves, attached to a laser-cut stainless-steel hypotube, allowing the stent to be unsheathed and deployed by pulling the hypotube relative to the inner wire, reducing friction and facilitating the deployment of stents with minimal radial force on the catheter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If covered stents are compressed into small diameter catheters for minimally-invasive delivery, then the device can be delivered through tortuous anatomy, but excessive friction between the stent and catheter wall occurs
Solution Approach 1:
A lubricious inner lining (such as PTFE) is introduced as an intermediary layer between the stent and the catheter wall. This mediator reduces direct contact and friction between the two surfaces, enabling the stent to be pushed through tortuous anatomy with minimal resistance while maintaining the minimally-invasive delivery approach
Solution Approach 2:
The stent is covered with a thin-film lubricious coating that acts as a flexible shell. This thin film reduces the coefficient of friction between the stent surface and the catheter wall, allowing the compressed stent to slide more easily through the catheter during delivery through complex vascular pathways
2Area of moving object
If the stent surface area is increased to provide better coverage, then the stent can cover more vessel surface, but the friction with catheter wall increases significantly
Solution Approach 1:
A thin-film lubricious coating is applied to the entire surface of the stent, including the increased surface area regions. This thin film maintains low friction characteristics across the expanded surface area, allowing larger stents to be delivered through catheters without proportionally increased resistance
Solution Approach 2:
The stent is constructed as a composite structure combining the metallic stent framework with a lubricious coating layer. This composite material approach allows the stent to maintain both structural integrity and low-friction surface properties, enabling larger surface area coverage without excessive friction during delivery
3Volume of moving object
If the stent is compressed to fit into the catheter, then the device can be delivered minimally-invasively, but the stent exerts radial force on the catheter wall causing friction
Solution Approach 1:
A thin-film lubricious coating is applied to the compressed stent surface. This thin film acts as a cushioning layer that reduces the coefficient of friction between the compressed stent and catheter wall, allowing the stent to be pushed through the catheter with minimal radial force requirement
Solution Approach 2:
The friction coefficient between the stent and catheter wall is changed by applying a lubricious coating. This parameter change allows the compressed stent to exert reduced radial force on the catheter wall during delivery, enabling minimally-invasive delivery of larger stents
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 effectively reduces friction and shear forces, enabling the efficient delivery and deployment of endovascular devices, such as thin-film covered stents, by minimizing contact with the catheter wall and allowing self-expansion of the stent at the target site.
Implementation Method 1
the sheath comprises polytetrafluoroethylene (PTFE)
Implementation Method 2
The system effectively reduces friction and shear forces, enabling the efficient delivery and deployment of endovascular devices
Data Source
AI summary
Systems, methods, and apparatus for delivery systems for endovascular devices are disclosed herein. In one or more embodiments, a delivery system comprises a stent comprising a mesh. Further, the delivery system comprises a shaft comprising an inner lumen. Also, the delivery system comprises a sheath encasing the stent. In one or more embodiments, the stent and a first portion of the sheath is connected to an end of a wire, and a second portion of the sheath is folded back and connected to an end of the shaft. Further, the delivery system comprises the wire traversing within the inner lumen of the shaft such that when the shaft is pulled back relative to the wire, the sheath splits open thereby unsheathing and deploying the stent.