Clot Retrieval Device Tubular Shield Friction Control
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Solution Overview
Problem
Mechanical thrombectomy devices cause abrasion and damage to blood vessel walls during clot retrieval due to the force required to dislodge and retract clots, leading to potential dissection or thrombus formation.
Innovation Solution
A clot retrieval system featuring a tubular shield element with a lower coefficient of friction inner surface and a higher friction outer surface, which reduces the force exerted on the vessel walls by distributing the tension across the outer surface of the shield, minimizing abrasion and friction during clot retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If force is applied to dislodge and retract the clot through the stentriever device, then the clot can be removed from the vessel, but abrasion and damage occur to the vessel wall
Solution Approach 1:
A tubular shield element is introduced as an intermediary component between the elongate shaft and the vessel wall. This shield element has a low friction coefficient inner surface that contacts the shaft, allowing smooth retraction, and a high friction coefficient outer surface that contacts the vessel wall, preventing slip and abrasion. The shield element thus mediates the interaction between the retrieval device and vessel wall, enabling clot removal while protecting the vessel from damage.
Solution Approach 2:
The shield element utilizes different friction coefficients on its inner and outer surfaces to resolve the contradiction. The inner surface has a low friction coefficient to minimize resistance during shaft retraction, while the outer surface has a high friction coefficient to prevent slipping against the vessel wall. This parameter change in friction characteristics allows the device to achieve both easy retraction and vessel protection simultaneously.
2Productivity
If the elongate shaft is retracted through the vessel, then the clot can be retrieved, but tension is placed on the vessels causing potential dissection or perforation
Solution Approach 1:
The tubular shield element serves as a mediator that distributes the tensile forces generated during clot retrieval across its extended surface area rather than concentrating them on a small shaft. This force distribution reduces the stress on any single point of the vessel wall, thereby preventing dissection or perforation while maintaining effective clot retrieval capability.
Solution Approach 2:
The shield element extends the interaction interface from a one-dimensional shaft to a two-dimensional tubular surface. This dimensional expansion allows the forces to be distributed across a larger area, reducing the mechanical stress on the vessel wall and improving vessel integrity during the retrieval process.
3Ease of operation
If a low friction surface is used on the shaft, then retraction is easier, but the device may slip within the vessel wall
Solution Approach 1:
Different regions of the shield element are assigned different friction characteristics tailored to their specific functions. The inner surface contacting the shaft has low friction to enable smooth retraction, while the outer surface contacting the vessel wall has high friction to prevent slipping. This local differentiation of friction properties resolves the contradiction between ease of operation and device stability.
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 system significantly reduces the force required for clot retrieval, minimizing vascular damage and the risk of complications such as dissection or thrombus formation, while preventing accidental retraction of the device into the microcatheter.
Implementation Method 1
the tubular shield element having a lower coefficient of friction inner surface and a higher friction outer surface
Data Source
AI summary
A clot retrieval system comprises an elongate member having a proximal end and a distal end, and a clot engaging element at the distal end of the elongate member the clot engaging element having a collapsed delivery configuration and an expanded deployed configuration. The force that is applied on retraction of the elongate member is transmitted to the clot engaging element.