Flexible Catheter Shaft with Radially Expandable Laser Cut Frame

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Solution Overview

Problem

Conventional catheters face challenges in accessing small, remote, and tortuous blood vessels due to stiffness issues, kinking, and friction during assembly, which complicates the delivery of auxiliary devices and affects the integrity and flexibility required for intravascular procedures.

Innovation Solution

A radially expandable catheter support tube with circumferentially discontinuous ribs and interlocking segments allows for controlled axial and lateral stiffness, enabling easy assembly over a liner and reducing friction, while varying segment pitches and polymer jackets tailor stiffness profiles for different sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the catheter shaft is made with continuous braided wires or metallic support frame, then tensile stiffness and compressive stiffness are improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvetensile stiffnessVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The catheter shaft is segmented into discrete ribs rather than using continuous braided wires or a solid metallic frame. These ribs are spaced apart axially and can be independently formed, simplifying manufacturing while maintaining structural integrity. The segmentation allows each rib to be manufactured separately and then assembled, reducing overall manufacturing complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The catheter shaft uses ribs with varying cross-sectional shapes, sizes, and spacing at different axial locations to provide locally optimized mechanical properties. This allows different sections of the catheter to have different stiffness characteristics tailored to specific functional requirements, achieving both strength and manufacturing efficiency.

Inventive Principle:

Principle #3Local quality

2Strength

If the catheter shaft is made with continuous braided wires or metallic support frame, then compressive stiffness is improved, but the ease of manufacture deteriorates

Engineering Contradiction:

Improvecompressive stiffnessVSAvoidease of manufacture

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

3Device complexity

If the inner diameter of the support frame is reduced to match the outer diameter of the inner liner, then the device complexity is reduced, but the ease of operation during assembly deteriorates due to excessive friction

Engineering Contradiction:

Improvedevice complexityVSAvoidease of assembly

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The catheter shaft is designed with radial expandability, allowing it to dynamically change its inner diameter during assembly. The shaft can be expanded radially to increase the clearance between the shaft outer surface and the inner liner, significantly reducing friction during the assembly process. After assembly, the shaft returns to its normal collapsed state, maintaining a compact profile.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The inner diameter of the catheter shaft is changed from a fixed small dimension to a variable dimension that can be temporarily increased during assembly. This parameter change allows the shaft to be assembled over the inner liner with reduced friction, then return to its normal operating dimension.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If the catheter shaft is made stiffer to improve pushability and stability, then the reliability is improved, but the flexibility to navigate tortuous vessels deteriorates

Engineering Contradiction:

Improvepushability and stabilityVSAvoidflexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20240091492A1Flexible catheter shaft frame with seam

Publication Date: 2024.03.21 NEURAVI

AI summary

The designs herein can be for a flexible and kink-resistant catheter with a support tube which can be radially expanded to enable it to be slid over an inner liner on a mandrel during assembly. The designs are flexible enough to allow the catheter to access remote vessel occlusions but also benefit from good compressive and tensile stiffness. The designs can have a laser cut frame with interlocking structure of circumferentially discontinuous rib struts. The discontinuities can be aligned to form at least one continuous axial seam which is separable to allow for the radial expansion during manufacturing. A series of polymeric outer jackets can coat or encapsulate the struts of the frame, giving variable stiffness and preventing disengagement of the interlocking structure while the catheter is pushed through tortuous anatomy.