Segmented Stent Delivery Sheath for Pushability and Break Resistance
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Solution Overview
Problem
Existing delivery sheaths for vascular stents face challenges in balancing inner and outer diameters, pushing performance, and resistance to breaking and stretching, especially when dealing with stents of larger radial sizes, which can affect the success and safety of interventional surgery.
Innovation Solution
A conveyor system with a delivery sheath design featuring a moderate inner diameter and outer diameter, enhanced by a layered structure of PTFE, stainless steel wire woven net, and Pebax tubes, along with a sliding mechanism and a handle system, ensuring good pushing performance and resistance to breaking and stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the inner diameter of the delivery sheath is increased to accommodate larger compressed stents, then the carrying capacity is improved, but the wall thickness decreases leading to reduced pushing performance and resistance to breaking
Solution Approach 1:
The delivery sheath is divided into three distinct segments: loading portion, pushing portion, and connecting portion. Each segment serves a specific function - the loading portion accommodates the stent with larger inner diameter, while the pushing portion maintains smaller inner diameter for better pushing performance. This segmentation allows the sheath to simultaneously achieve both large carrying capacity and strong pushing performance without compromising wall thickness in critical areas.
Solution Approach 2:
Different portions of the delivery sheath are designed with different local qualities - the loading portion has larger inner diameter for stent accommodation, while the pushing portion has smaller inner diameter and optimized wall thickness for mechanical strength. This local differentiation ensures that each section has the appropriate properties for its specific function, resolving the contradiction between carrying capacity and structural strength.
2Ease of operation
If the outer diameter of the delivery sheath is reduced to improve navigability, then the ease of operation is improved, but the wall thickness decreases leading to reduced resistance to breaking and stretching
Solution Approach 1:
The delivery sheath is segmented into loading, pushing, and connecting portions with different dimensional characteristics. The pushing portion is specifically designed with optimized outer diameter and wall thickness to maintain high strength while keeping the overall profile compact for navigability. This segmentation allows the sheath to achieve both good navigability and high resistance to breaking and stretching.
Solution Approach 2:
The pushing portion is designed with specific local quality parameters - optimized outer diameter for navigability and enhanced wall thickness for resistance to breaking and stretching. This local quality differentiation allows the sheath to be navigable while maintaining the structural integrity needed to withstand high pull forces during stent release.
3Strength
If the wall thickness of the delivery sheath is increased to improve pushing performance and resistance to breaking, then the strength is improved, but the outer diameter increases making navigation more difficult
Solution Approach 1:
The delivery sheath is divided into segments with different wall thickness characteristics. The pushing portion has optimized wall thickness for high pushing performance and resistance to breaking, while other portions have reduced wall thickness to maintain compact outer diameter for navigability. This segmentation resolves the contradiction by localizing the thick-walled section only where mechanically critical.
Solution Approach 2:
The pushing portion is designed with enhanced local quality - increased wall thickness specifically in the region where pushing performance is critical. This localized quality enhancement allows the sheath to achieve high strength where needed while maintaining overall compact dimensions for easy navigation through blood vessels.
Data Source
AI summary
A conveyor and a lumen apparatus delivery system. The conveyor includes a sheath core tube, a delivery sheath and an operating handle. The proximal end of the sheath core tube and the proximal end of the delivery sheath are both connected to the operating handle. The delivery sheath and the sheath core tube are both a hollow tube. The delivery sheath is sleeved on the sheath core tube in an axially slidable manner, and the delivery sheath and the sheath core tube cooperatively define a storable cavity. The delivery sheath includes a loading portion, a pushing portion and a connecting portion. The proximal end of the loading portion is connected to the distal end of the pushing portion; the proximal end of the pushing portion is connected to the distal end of the connecting portion, and the proximal end of the connecting portion is connected to the operating handle.