Embolectomy Device Support Structure Radial Expansion
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Solution Overview
Problem
Existing embolectomy devices tend to stretch and reduce their profile when subjected to tension after deployment in blood vessels, leading to failure in engaging and capturing embolic obstructions, especially hard or dense clots, due to insufficient radial expansion force.
Innovation Solution
Incorporating a support structure with interconnected struts and connectors that bias to expand from a radially constrained to an expanded configuration, assisted by an elongate central support member or flexible sections, to maintain radial expansion and prevent undesirable stretching, ensuring effective engagement and retrieval of embolic obstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the embolectomy device is made with flexible struts to allow radial compression for delivery, then the device can be delivered through tortuous vasculature, but the device lacks sufficient radial expansion force to engage hard or dense clots
Solution Approach 1:
The device divides the support structure into multiple interconnected struts forming open cell structures. Each strut is individually flexible for delivery, but collectively they provide sufficient radial expansion force when deployed, resolving the contradiction between individual flexibility and collective strength
Solution Approach 2:
The device uses Nitinol, a shape memory alloy, that combines superelasticity for flexibility during delivery with the ability to generate sufficient radial force when expanded. This composite material property resolves the contradiction between softness for navigation and hardness for clot engagement
2Force
If the device is made with rigid structure to provide sufficient radial force for clot engagement, then the device can effectively capture embolic obstructions, but the device cannot be compressed for delivery through catheters
Solution Approach 1:
The device transitions dynamically from a compressed flexible state during delivery to an expanded rigid state during clot engagement. The struts are designed to be flexible when compressed but become rigid when expanded, allowing the device to satisfy both contradictory requirements at different operational stages
Solution Approach 2:
The device changes its physical parameters (rigidity, radial force) through the expansion process. When compressed, the struts are flexible with low radial force; when expanded, the struts become rigid with high radial force, resolving the contradiction between deliverability and clot engagement capability
3Shape
If the device is expanded to engage clots, then the device can capture embolic obstructions, but the device stretches and reduces profile when subjected to tension, leading to failure in capturing hard clots
Solution Approach 1:
Instead of allowing the struts to stretch outward when subjected to tension, the design inverts the response by having the struts bend inward toward the central axis. This inward bending prevents profile reduction and maintains radial expansion stability under tensile loads, resolving the contradiction between shape maintenance and tension resistance
4Force
If the struts are made thicker to provide sufficient radial force, then the device can engage hard clots, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The device segments the radial force generation function across multiple thin struts rather than using fewer thick struts. Each thin strut is easy to manufacture, but collectively they provide the necessary radial expansion force, resolving the contradiction between force generation and manufacturing simplicity
Solution Approach 2:
The struts have non-uniform cross-sectional properties along their length, with thicker sections at connection points for strength and thinner sections in the middle for flexibility. This local quality variation optimizes both the radial force generation capability and the ease of manufacture
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 support structure facilitates sustained radial expansion of the embolectomy device, enhancing its ability to engage and capture embolic obstructions, while allowing for a desirable reduction in profile for repositioning and withdrawal, thereby improving the device's effectiveness in removing clots from blood vessels.
Implementation Method 1
the support structure is configured to utilize elastic memory to bias expansion from a radially constrained configuration to a radially expanded configuration
Implementation Method 2
The embolectomy device 12 is composed of shape memory, self-expandable and biocompatible materials, such as Nitinol
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~3D
AI summary
An embolectomy device (112) includes a clot engaging structure comprising a plurality of interconnected struts (124) forming an open cell structure having an inner lumen, wherein the clot engaging structure is biased to expand or otherwise expandable from a radially constrained configuration to a radially expanded configuration when released from a delivery catheter into a blood vessel; and a support structure (200) positioned within the inner lumen of the clot engaging structure, the support structure (200) comprising a plurality of connectors (230) connected to respective struts (124) of the clot engaging structure, wherein the support structure (200) connectors are biased to move or otherwise movable from a radially constrained configuration to a radially expanded configuration to thereby cause or otherwise assist and/or facilitate and maintain expansion of the open cell clot engaging structure.