Expandable Catheter Tip for Low-Shear Clot Retrieval
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Solution Overview
Problem
Conventional clot retrieval catheters face challenges in navigating tortuous blood vessels due to large size, lack of flexibility, and ineffective clot removal, particularly in small, remote, and highly tortuous vessels like those in the neurovascular bed, where clots often shear or become lodged during extraction.
Innovation Solution
A large bore clot retrieval catheter with a low shear tip that features a proximal elongate shaft and a distal expansile section capable of radial expansion, supported by wire braided segments and axial spine members, allowing for atraumatic navigation and reduced clot shearing by accommodating clots through progressive compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional catheters use a fixed-size tip, then the catheter structure is simple, but the clot cannot be accommodated without compression leading to shearing
Solution Approach 1:
The catheter tip is designed with an expandable structure that transitions from a compressed delivery configuration to an expanded clot capture configuration. The tip includes expandable elements such as balloons or self-expanding frames that increase the internal diameter upon deployment, allowing the catheter to adapt its size to accommodate clots of varying dimensions without causing shearing during retrieval.
2Productivity
If the catheter has a large bore lumen, then clot retrieval effectiveness is improved, but the catheter outer diameter increases making navigation through tortuous vessels difficult
Solution Approach 1:
The catheter employs a nested configuration where the expandable tip and large bore lumen are contained within a smaller delivery profile during the advancement phase. The tip elements are compressed or collapsed within the catheter body, allowing the entire assembly to navigate through tortuous vessels and small access points. Upon reaching the target site, the tip expands to provide the large lumen needed for effective clot retrieval.
3Strength
If the catheter uses a stiff supporting braid, then structural strength is improved, but flexibility and ability to navigate tortuous vessels is reduced
Solution Approach 1:
The catheter employs differentiated structural properties along its length. The proximal shaft contains a stiff supporting braid or reinforcement structure to provide pushability and structural integrity during advancement. The distal tip section, however, uses a more flexible construction with lower radial stiffness to allow bending and conforming to tortuous vessel geometry. This local variation in mechanical properties enables the catheter to maintain both strength and flexibility where needed.
4Reliability
If the catheter tip expands radially to capture clot, then clot retention is improved, but the outer diameter increases blocking passage through guide and sheath
Solution Approach 1:
The catheter is delivered to the target site in a compressed or collapsed state within the guide catheter and sheath, minimizing its outer diameter for safe passage. Once positioned at the clot location, the tip is deployed and expanded to the larger diameter needed for clot capture and retention. This sequential transformation allows the catheter to achieve both small delivery profile and large clot capture capacity without interference.
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 catheter design enhances clot management by minimizing shearing and trauma to vessels, enabling effective retrieval of clots from complex vascular structures while maintaining the ability to recover its shape for further navigation and aspiration.
Implementation Method 1
a wire braided structure comprising a nominal inner diameter and configured to radially expand passively due to forces from ingesting the clot to a larger expanded inner diameter
Implementation Method 2
utilizing local radial forces generated as the clot is ingested proximally to radially expand the wire braided structure of the innermost aspiration catheter
Data Source
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AI summary
The designs and methods disclosed herein are for a clot retrieval catheter with a large bore shaft and a distal braid-supported tip that is expandable. A distal expansile section of the braid-supported tip can have a delivery inner diameter approximately equal to the inner diameter of the shaft. The braid of the tip can have a decreasing braid angle distally so that the tip can expand to a larger expanded inner diameter when impinged radially by an ingested clot to manage the clot and prevent shearing of clot fragments. The wires of the tip braids can follow one spiral direction distally and then invert proximally back on themselves to form the other spiral direction of the braid. This inversion of the wires results in atraumatic distal hoops at the distal termination of the braid. Designs can further have spines capable of resisting elongation of the catheter shaft during a procedure.