Removable Sheath Assembly for Polymer Scaffold Recoil
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Solution Overview
Problem
Polymer scaffolds face challenges in maintaining integrity and preventing recoil during crimping and delivery due to their material properties, which affect the scaffold-balloon engagement and delivery profile, necessitating improved sheath designs for radial constraint and easy removal.
Innovation Solution
The use of a sheath assembly with a constraining and protecting sheath configuration that applies a radial constraint to reduce recoil and facilitate safe, intuitive removal, including a two-piece sheath design with a constraining sheath and a protecting sheath that extends beyond the catheter distal end to maintain the scaffold's engagement with the balloon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer scaffold is crimped to a balloon catheter, then the scaffold can be delivered to the target site, but the scaffold is prone to recoil and dislodgment due to material properties
Solution Approach 1:
A sheath is introduced as an intermediary component between the scaffold and the external environment. The sheath applies radial constraint to the crimped scaffold, preventing recoil and maintaining engagement with the balloon catheter during delivery. The sheath is subsequently removed at the target site to allow scaffold deployment.
Solution Approach 2:
The sheath applies preliminary radial constraint to counteract the inherent recoil tendency of the polymer scaffold before deployment. By constraining the scaffold in its crimped state during delivery, the sheath prevents the harmful recoil action that would otherwise occur due to the scaffold's material properties.
2Stability of the object's composition
If a sheath is used to constrain the scaffold radially, then recoil is reduced, but the sheath must be removed which risks scaffold dislodgment
Solution Approach 1:
The sheath is designed with features that enable controlled removal after serving its constraining function. The sheath maintains radial constraint during delivery, then is removed in a controlled manner at the target site after the scaffold has been positioned, minimizing the risk of dislodgment.
3Reliability
If the sheath extends beyond the catheter distal end, then the scaffold engagement is maintained, but the device complexity increases
Solution Approach 1:
The sheath is divided into functional segments: a constraining portion that contacts the scaffold to prevent recoil, and an extension portion that extends beyond the catheter distal end to maintain engagement during removal. This segmentation allows each portion to perform its specific function while managing overall device 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
The sheath assembly effectively maintains the scaffold-balloon engagement and reduces recoil, ensuring the scaffold remains securely attached to the balloon until deployment, minimizing the risk of dislodgment or damage during removal.
Implementation Method 1
a sheath assembly with a constraining and protecting sheath configuration that applies a radial constraint to reduce recoil
Data Source
AI summary
A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. A sheath is placed over the crimped scaffold after crimping to reduce recoil of the crimped polymer scaffold and maintain scaffold-balloon engagement relied on to hold the scaffold to the balloon when the scaffold is being delivered to a target in a body. The sheath is removed by a health professional either by removing the sheath directly or using a tube containing the catheter.