Actuated Clot Retrieval Catheter with Shape Memory Frame
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Solution Overview
Problem
Conventional clot retrieval catheters face challenges in accessing and removing acute blockages from blood vessels due to small diameters, flexibility issues, and inefficiencies in aspiration, particularly in navigating tortuous neurovascular pathways and managing fibrin-rich clots that can fragment and embolize.
Innovation Solution
An actuated clot retrieval catheter system utilizing a shape memory material frame that transitions between collapsed and expanded configurations via electrical heating and cooling, allowing for enhanced aspiration efficiency and improved clot capture within the catheter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the catheter diameter is reduced to access small neurovascular vessels, then the ability to navigate tortuous vasculature is improved, but the efficiency of aspiration and clot retrieval capability deteriorates
Solution Approach 1:
The catheter employs a dynamic tip design that can change configuration between a delivery configuration (small profile for navigation) and an expanded configuration (large opening for aspiration). The tip includes an expandable frame structure that transitions from a compressed state during delivery to an expanded state at the target site, allowing the catheter to adapt its diameter according to operational requirements.
Solution Approach 2:
The expandable frame structure is nested within the catheter body in a compressed state during delivery, similar to nested dolls. Once positioned at the target vessel, the frame is deployed outward from the catheter body to create a large aspiration opening, then can be retracted back into the catheter for retrieval.
2Ease of operation
If the catheter tip is made fixed and small in size, then the catheter can be advanced through small vessels, but the ability to capture and retrieve large clots deteriorates
Solution Approach 1:
The tip is designed with dynamic expandability, transitioning from a small profile during advancement to a large capture configuration when engaged with the clot. The expandable frame can open to create a large mouth for clot engagement, then close to secure and retrieve the clot.
Solution Approach 2:
The tip structure changes its physical parameters (opening size, shape) in response to operational needs. The frame can be actuated to change from a closed delivery state to an open capture state, and the opening angle can be adjusted to optimize clot engagement based on clot size and morphology.
3Productivity
If strong aspiration force is applied to remove clots, then clot removal speed is improved, but clot fragmentation and distal embolization worsen
Solution Approach 1:
The tip performs preliminary engagement and securement of the clot before aspiration begins. The expandable frame establishes firm contact with and grip on the clot, creating a secure mechanical connection that prevents fragmentation during the subsequent aspiration process.
Solution Approach 2:
The system replaces direct mechanical pulling forces with controlled aspiration through the expandable frame. The frame acts as a secure interface that distributes aspiration forces evenly across the clot, reducing stress concentrations that would cause fragmentation.
4Adaptability or versatility
If the catheter is made highly flexible to navigate tortuous vessels, then navigability is improved, but axial stiffness and smooth advancement capability deteriorate
Solution Approach 1:
The catheter is divided into segments with different mechanical properties. The proximal portion maintains higher stiffness for pushability and control, while the distal portion incorporates flexible elements for navigation. The intermediate sections use gradual transitions or compliant mechanisms to balance these requirements.
Solution Approach 2:
The catheter construction employs composite materials with varying mechanical properties along its length. Different polymer formulations, braid patterns, or structural configurations are used in different sections to achieve the desired balance between flexibility for navigation and stiffness for advancement.
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 provides improved access and retrieval of clots by expanding the catheter's inner diameter for effective clot capture and aspiration, reducing fragmentation and embolization, and ensuring safe navigation through complex vascular structures.
Implementation Method 1
The frame can include a shape memory material that enables the frame, or a portion thereof, to transition from a martensite phase to an austenite phase when heated to above the material's austenite finish temperature
Implementation Method 2
The electronic circuit can provide a first current to the first conductive wire... At least a first portion of the frame can be expandable from a collapsed configuration to an expanded configuration upon being heated by the first current
Implementation Method 3
The system can include a thermoelectric cooling circuit in electrical communication with the frame. The at least a first portion of the frame can be collapsible from the expanded configuration to the collapsed configuration upon removal of heat by the thermoelectric cooling circuit
Data Source
AI summary
Devices described herein include an actuated clot retrieval catheter system. The system includes a catheter having a frame disposed proximate the distal end of the catheter. The frame expands to form a seal with the inner wall of a vessel. In some examples, the frame also captures a clot for removal from the vessel. The frame is manufactured from a shape memory material that can be heat set into a predetermined shape. An electrical connection to an electronic circuit causes a current to run through the frame. The electrical resistance of the shape memory material causes the frame to heat and transition from a martensite to an austenite phase. When the frame is heat set into an expanded configuration, the current causes the frame heat and expand. When the frame is heat set into a closed configuration, the current causes the frame heat and collapse upon a clot.