Nitinol Conical Retrieval Device for Clot Capture
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Solution Overview
Problem
Conventional thrombectomy devices face challenges such as clot fragmentation, difficulty in removing clots from narrow vessels, risk of vessel wall penetration, and incomplete clot capture due to size and stiffness issues, especially in small tortuous vessels like those in the brain.
Innovation Solution
An obstruction removal assembly featuring an elongate catheter with an expandable retrieval device that forms a tapered cone for capturing obstructions, which can be rewrapped and withdrawn into the catheter, utilizing a shape memory material like Nitinol for conical expansion and compression, allowing for secure clot capture and removal without aspiration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a smooth rounded tip is used on corkscrew devices to prevent vessel wall penetration, then vessel wall safety is improved, but the device cannot effectively screw into the clot resulting in clot fragmentation
Solution Approach 1:
The device employs different tip geometries at different locations: a sharp distal tip for effective clot penetration and capture, while the proximal portion maintains a smoother configuration for vessel wall safety. This local differentiation allows the device to simultaneously achieve effective clot engagement and minimize vessel wall damage risk.
Solution Approach 2:
The corkscrew device is divided into multiple segments with different functional characteristics along its length. The distal tip is designed with sharp features for clot penetration, while the proximal segments have smoother surfaces for safe vessel navigation. This segmentation allows each portion to perform its specific function optimally without compromising the other.
2Object-affected harmful factors
If a large bead or ball is applied to the tip to protect the vessel wall, then vessel wall protection is improved, but the device pushes the clot distally rather than capturing it
Solution Approach 1:
Instead of placing a large protective bead at the distal tip that would prevent clot engagement, the invention inverts the approach by using a sharp distal tip for clot penetration while placing protective features at the proximal portion of the device that is in contact with the vessel wall during insertion.
3Productivity
If conventional thrombectomy devices are made large and stiff for effective clot removal, then clot removal capability is improved, but they cannot navigate small tortuous vessels in the brain
Solution Approach 1:
The device incorporates dynamic flexibility through its elongated shaft design that can bend and conform to tortuous vessel pathways while maintaining the capability to engage and remove clots. The shaft's dynamic properties allow it to adapt to varying vessel geometries without sacrificing clot removal effectiveness.
Solution Approach 2:
The device employs a flexible shaft construction that allows navigation through small and tortuous vessels. The flexible structure maintains sufficient stiffness at the distal tip for effective clot engagement while the proximal portions remain flexible for safe navigation through complex vasculature.
4Stability of the object's composition
If a central mandrel wire is used for device support, then structural stability is improved, but it displaces clots making it difficult to capture all clot material
Solution Approach 1:
The invention removes the central mandrel wire structure that was causing clot displacement. Instead, the device relies on its flexible shaft and distal tip geometry to engage and capture clot material, allowing complete contact with the clot without internal structures that would create displacement zones.
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
Enables safe and complete removal of clots from small and tortuous vessels by minimizing clot fragmentation and vessel wall risk, facilitating retrieval of clots without breaking them and ensuring all clot material is captured, even in narrow vessels.
Implementation Method 1
utilizing a shape memory material like Nitinol for conical expansion and compression
Data Source
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AI summary
A clot removal device (10) includes a conical retrieval member (14) affixed to a wire (12) The conical retrieval member (14) has an apex (16) at its distal end, and a base that forms an opening (18) into a cavity The conical retrieval member (14) is formed from a thin sheet of Nitinol film, and expands into its conical configuration at body temperature The clot removal device (10) can be used physically to withdraw a blood clot (40) from a blood vessel (42) without requiring aspiration The member (14) can be pulled by a cord (90) to cause it to rewrap onto itself, in so doing to capture an obstruction such as a thrombus.