Stent Delivery Outer Sheath Heat Shrink Support Member
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Solution Overview
Problem
Stent device delivery systems face challenges with high frictional forces during deployment, leading to material strength issues and potential reliability problems, particularly in rolling outer sheath systems where the fold-over portion must slide against a more proximal portion, and in pullback systems where friction between the stent device and outer sheath requires overcoming significant forces.
Innovation Solution
A stent device delivery system with an outer sheath comprising a laminated structure of polymeric materials, including a first layer, a reinforcement layer, and a glue layer, which provides strength and inhibits necking, allowing for a thin, reliable deployment without excessive force, and a pull member embedded in the glue layer for uniform force transfer, along with a tapering stent bed profile to reduce deployment force and prevent sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a rolling outer sheath system is used, then deployment force is reduced compared to pullback systems, but the fold-over portion must slide against a proximal portion creating friction and potential reliability issues
Solution Approach 1:
A lubricious coating is applied to the inner surface of the outer sheath and/or the outer surface of the stent device to reduce friction during the rolling deployment process. This intermediary layer allows the fold-over portion to slide more smoothly against the proximal portion, maintaining low deployment force while improving reliability by preventing sticking and excessive wear
2Volume of moving object
If the outer sheath is made thinner to reduce profile, then the cross-sectional profile is reduced, but the material strength is compromised due to high frictional forces
Solution Approach 1:
The outer sheath is constructed as a composite structure combining a thin polymeric material with a lubricious coating layer. The base polymeric material provides the low-profile geometry, while the lubricious coating layer provides the necessary friction-reduction properties, allowing the thin-walled structure to withstand deployment forces without compromising strength or reliability
3Device complexity
If a pullback outer sheath system is used, then the construction is simpler with single-layer structure, but friction between the stent device and outer sheath requires overcoming significant forces
Solution Approach 1:
A lubricious coating is applied to the inner surface of the pullback outer sheath to reduce friction against the stent device during retraction. This intermediary layer significantly reduces the pulling force required to retract the outer sheath, maintaining the simplicity of the single-layer construction while overcoming the high frictional force problem
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 solution enables reliable and efficient radial expansion of the stent device with reduced deployment force, maintaining a low profile and enhancing the strength of the outer sheath, thereby improving the reliability and ease of delivery to the diseased vascular lumen.
Implementation Method 1
a glue layer radially between the first layer and the reinforcement layer
Implementation Method 2
a portion of the outer sheath is heat shrunk radially onto a relatively heat shrink resistant support member
Data Source
AI summary
A stent device delivery system and method of making. The stent device delivery system includes a stent device and an outer sheath overlaying the stent device in a radially compact, delivery configuration of the stent device. The system also includes a pull member for pulling proximally on to retract the outer sheath, wherein a portion of the outer sheath is heat shrunk radially onto a relatively heat shrink resistant support member in order to capture a distal portion of the pull member radially between the outer sheath and the heat shrink resistant support member.