Introducer Sheath Dual Reinforcing Elements Kink Resistance
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Solution Overview
Problem
Existing introducer sheaths face challenges with kinking and stretching issues during the deployment of longer or coated stents, which can lead to increased resistance and reduced effectiveness in maintaining the radial expansive forces, especially when using coil reinforcement alone.
Innovation Solution
The introducer sheath incorporates a braid reinforcement along a significant portion of its length, preferably over 50% to 90%, combined with a coil reinforcement at the distal end, to minimize stretching and maintain kink resistance, allowing for efficient deployment of stents by distributing the radial forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coil reinforcement is used in the introducer sheath, then kink resistance is improved, but the sheath stretches during withdrawal when deploying longer or coated stents
Solution Approach 1:
The reinforcing element is divided into two distinct segments: a braid portion and a coil portion. The braid is positioned at the proximal portion of the sheath while the coil is positioned at the distal portion. This segmentation allows each segment to perform its specialized function - the braid prevents stretching during withdrawal, while the coil provides kink resistance during navigation
Solution Approach 2:
Different reinforcing structures are applied to different portions of the sheath based on local requirements. The proximal portion (subject to withdrawal forces) receives braid reinforcement for stretching prevention, while the distal portion (subject to bending) receives coil reinforcement for kink resistance. This local differentiation optimizes performance at each location
2Strength
If the sheath wall is made thicker to improve kink resistance, then structural strength is improved, but the diameter of the interventional device that can be passed is reduced
Solution Approach 1:
The sheath employs a composite construction combining a thin-walled fluorocarbon tube with separate reinforcing elements (braid and coil). This composite approach provides the strength and kink resistance of thicker walls while maintaining the small diameter and flexibility of thin-walled construction, allowing both improved structural performance and preserved lumen capacity
3Ease of operation
If the sheath is made thinner to reduce entry opening size, then ease of insertion is improved, but kink resistance deteriorates
Solution Approach 1:
The sheath combines a thin-walled fluorocarbon tube with external reinforcing elements (braid and coil). This composite structure provides the flexibility and small profile of thin-walled construction for easy insertion, while the reinforcing elements supply the kink resistance that would otherwise require thicker walls
Data Source
AI summary
An introducer sheath for deploying a stent to a target site within a body passageway of a patient. The introducer sheath includes a tubular inner liner having a proximal portion, a distal portion, and an outer surface. A first reinforcing element, and a second reinforcing element are positioned along the outer surface of the inner liner. The first reinforcing element comprises a braid the second reinforcing element comprises a coil. The braid is positioned at the proximal portion of the inner liner and extends distally therefrom. The coil is positioned at the distal portion longitudinally adjacent the braid. The braid has a length that may extend about 90% of the length of the sheath. An outer jacket is positioned longitudinally around the reinforcing elements, and is connected to the inner liner between the respective wires of the braid and the coil.