Self-Expandable Clot Retrieval Device for Small Vasculature
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Solution Overview
Problem
Current distal mechanical thrombectomy devices face challenges in effectively engaging and retracting thrombi or emboli from extremely small and tortuous vasculature, limiting their efficacy in treating acute ischemic stroke and pulmonary embolism.
Innovation Solution
A self-expandable mechanical clot retrieval device with an elongate member and plurality of ring elements, made of shape memory materials like Nitinol, that collapses for delivery through a microcatheter and expands at the blockage site to engage and retract clots, utilizing tethers and biasing elements to maintain a retracted configuration during delivery and expand for clot engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the retrieval device is delivered through a microcatheter in a collapsed state, then the device can access extremely small and tortuous vasculature, but the device cannot effectively engage and retract thrombus from the blocked artery
Solution Approach 1:
The retrieval device is divided into multiple ring elements (first ring element, second ring element, etc.) that can independently expand and engage the clot. Each ring element comprises multiple struts that can be selectively engaged or disengaged, allowing the device to adapt to different vessel sizes and clot configurations while maintaining effective retrieval capability
Solution Approach 2:
The device transitions from a collapsed delivery configuration to an expanded retrieval configuration through the use of shape memory materials (Nitinol) and biasing elements. The ring elements dynamically change their structural state based on deployment conditions, enabling both microcatheter compatibility and effective clot engagement
2Reliability
If the ring elements are made self-expandable using shape memory material, then the device can reliably engage clot upon deployment, but the device complexity increases due to additional components like tethers and biasing elements
Solution Approach 1:
The tether and biasing element functions are merged into a single integrated component. The tether connects the ring element to the elongate member while simultaneously providing the biasing force through its elastic properties, eliminating the need for separate biasing springs or mechanisms and simplifying the overall device structure
Solution Approach 2:
The tether's elastic properties are utilized to provide biasing force, changing the approach from mechanical springs to elastic material-based biasing. This parameter change simplifies the device by using the inherent elastic recovery of the tether material rather than requiring complex mechanical biasing mechanisms
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 device efficiently and reliably removes thrombi or emboli from small vasculature by expanding at the blockage site, enhancing clot engagement and retrieval, thereby improving treatment outcomes for acute ischemic stroke and pulmonary embolism.
Implementation Method 1
the self-expandable ring elements are formed of shape memory material such as Nitinol
Implementation Method 2
a biasing element for biasing the clot engaging elements into a retracted delivery configuration against the elongate member; the biasing element being releasable to allow the clot engaging elements to expand into the deployed configuration
Data Source
AI summary
A clot retrieval device for removing clot from a blood vessel including a plurality of ring elements comprising a plurality of struts forming one or more closed cells having one or more crown elements and attached together by connecting tethers at connection points, a plurality of openings through which clot may pass and enter the device, each opening being disposed between respective ring elements. Each ring element can be self-expandable from a collapsed configuration to an expanded configuration wherein a radial force biases the ring elements toward the expanded configuration. At least one of the crown element terminates in an apex away from a center axis of the device.