Flexible Sheath With Polymer Coil And Braid
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Solution Overview
Problem
Current tubular medical devices face challenges with kinking, necking, and reduced torqueability, which hinder their effectiveness in minimally invasive procedures, and existing solutions compromise on trackability and pushability to facilitate splittability.
Innovation Solution
A tubular device with a coil and braid reinforcement, featuring a polymeric layer and optional metal or polymer coils, providing enhanced stiffness and flexibility, along with a splittable design for easier deployment of stents and grafts, maintains high trackability, pushability, and torqueability while resisting collapse and kinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a braid reinforcement is used in the catheter shaft wall, then torqueability and pushability are enhanced, but the catheter becomes susceptible to kinking
Solution Approach 1:
The catheter shaft employs a composite construction combining a braid reinforcement layer with a coil reinforcement layer. The braid provides enhanced torqueability and pushability, while the coil structure prevents kinking by maintaining structural integrity under compression. This composite approach allows both reinforcement types to work synergistically, achieving both improved operability and kinking resistance that neither reinforcement could provide alone.
2Reliability
If a coil is embedded in the catheter shaft wall, then kinking is inhibited, but the catheter becomes susceptible to necking and loses torqueability
Solution Approach 1:
The catheter shaft employs a composite construction combining a braid reinforcement layer with a coil reinforcement layer. The coil structure prevents kinking by maintaining structural integrity under compression, while the braid layer compensates for potential necking and enhances torqueability. This composite approach allows both reinforcement types to work synergistically, achieving both improved operability and kinking resistance that neither reinforcement could provide alone.
3Adaptability or versatility
If a sheath is used for deploying stents, then stent delivery is enabled, but retraction of the sheath becomes difficult for longer stents
Solution Approach 1:
The sheath is designed with a segmented structure featuring a proximal portion and a distal portion that can be independently manipulated. The distal portion has reduced structural integrity compared to the proximal portion, allowing it to be separated or detached more easily during retraction. This segmentation enables the operator to retract the sheath in stages, reducing the overall retraction force required and making deployment of longer stents more manageable.
Solution Approach 2:
The sheath design allows for extraction of the distal portion from the proximal portion during the deployment process. By separating the sheath into two functional segments, the operator can remove or detach the distal segment after stent deployment, significantly reducing the retraction distance and force required for the proximal segment. This extraction mechanism transforms a single difficult retraction action into a two-step process that is mechanically easier to perform.
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 device achieves high resistance to collapse, necking, and kinking, with improved torqueability and pushability, allowing for easier deployment of stents and grafts, especially longer ones, and reduces the complexity of retraction, making procedures more efficient and less cumbersome for physicians.
Implementation Method 1
A polymeric bonding layer is positioned over and contacts the coil, or both the coil and the braid. The polymeric bonding layer maintains the coil in the stressed radially expanded condition, and is bonded to an inner liner
Data Source
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AI summary
A medical device including a tube having a coil fitted around at least a part of an inner liner, such as PTFE, and a braid extending over at least part of the coil. A polymeric layer is positioned over the braid to adhere to the inner liner. A portion of the coil advantageously comprises a polymer, such as PEEK, while the coil may also have a metal portion. The polymer coil may extend along at least at the proximal region of the tube, and the metal coil may extend along at least at the distal region of the tube. A polymer coil, a metal coil or any combination thereof can extend along the intermediate region of the tube. The polymer coil can be configured so that the tube is longitudinally splittable with a cutting instrument.