Dual-Layer Stent Delivery for Anchoring and Flow Diversion
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Solution Overview
Problem
Existing vascular embolization methods for treating aneurysms and other vascular abnormalities face challenges in effectively blocking blood flow and preventing emboli dislodgment, particularly in areas prone to thrombus formation, with existing stents lacking sufficient anchoring force and porosity control.
Innovation Solution
A stent delivery device comprising a dual-layer stent structure with an outer anchoring stent and inner flow-diverting layer, made from woven nitinol wire, which provides enhanced anchoring and blood flow modification capabilities, and a delivery system using a pusher member with marker bands for precise deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer stent is used, then the device complexity is low, but the anchoring force and blood flow control are insufficient
Solution Approach 1:
The stent is divided into two functional layers: an outer anchoring stent layer and an inner flow-diverting layer. The outer layer provides structural support and anchoring force to the vessel wall, while the inner layer controls blood flow into the aneurysm. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between anchoring force and device complexity.
Solution Approach 2:
The inner flow-diverting layer is nested within the outer anchoring stent layer, creating a dual-layer concentric structure. This nesting arrangement allows the flow-diverting layer to be supported by the outer layer while maintaining independent functionality. The inner layer can be delivered through the outer layer's lumen, simplifying the delivery system while achieving both anchoring and flow diversion functions.
2Reliability
If stent porosity is increased, then blood flow through the aneurysm is reduced, but emboli may still dislodge and migrate
Solution Approach 1:
The stent structure implements local quality differentiation through its dual-layer design with varying porosity. The inner flow-diverting layer has lower porosity to entrap emboli and particulates, while the outer anchoring layer has higher porosity to maintain blood flow through the treated vessel segment. This local variation in porosity allows the device to simultaneously achieve emboli entrapment and controlled blood flow, resolving the contradiction between these two requirements.
3Ease of operation
If deployment forces are reduced, then the delivery system is easier to operate, but anchoring force may be compromised
Solution Approach 1:
The dual-layer stent structure exhibits dynamic behavior during deployment. The outer anchoring layer is designed to expand first and engage with the vessel wall, providing initial anchoring force. The inner flow-diverting layer then expands, benefiting from the support already provided by the outer layer. This sequential, dynamic deployment allows the system to achieve strong anchoring force while maintaining relatively low deployment forces, as each layer assists the other during the expansion process.
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 dual-layer stent achieves improved anchoring and blood flow diversion, reducing emboli migration and thrombus formation, with reduced deployment forces and enhanced tracking and deployment characteristics.
Implementation Method 1
made from woven nitinol wire
Implementation Method 2
made from woven nitinol wire
Data Source
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Figure 6
AI summary
A stent delivery device is disclosed which comprises a pusher having a friction region of larger diameter near a distal end of the pusher; a stent compressed over the friction region and having an inner surface in contact with the friction region ; and, a sheath positioned over the pusher.