Helical Laser-Cut Catheter Shaft for Pushability and Flexibility
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Solution Overview
Problem
Current catheter technologies face challenges in navigating tortuous body lumens and crossing chronic total occlusions due to limitations in flexibility and torque transmission, leading to procedural failures in treating vascular blockages.
Innovation Solution
A flexible catheter tube with a laser-cut section in a continuous helical pattern forming interlocking teeth, combined with a polymeric bi-layer and thin polymer coating, allowing for enhanced flexibility and axial push force transmission without kinking, enabling effective navigation through complex vascular anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a stiff tube is used to transmit axial push force, then the push force transmission is improved, but the flexibility and ability to navigate tortuous vessels deteriorates
Solution Approach 1:
The catheter shaft is segmented into multiple sections with different flexibility characteristics. The distal section has a tighter spiral cut pattern providing greater flexibility, while the proximal section has a looser pattern providing stronger push force transmission. This segmentation allows each section to optimize its function while working together as a unified system.
Solution Approach 2:
Different sections of the catheter shaft are given different local qualities through varying the spiral cut parameters. The pitch, depth, and angle of the spiral cuts are locally adjusted along the shaft length to create a gradient of flexibility and torque transmission properties, allowing the catheter to be flexible at the tip while maintaining pushability from the proximal end.
2Adaptability or versatility
If a flexible shaft with tight spiral cut is used to improve flexibility, then the ability to navigate tortuous vessels is improved, but the torque transmission capability deteriorates
Solution Approach 1:
The shaft is divided into segments with different spiral cut densities. The distal segment uses tighter cuts for flexibility, while the proximal segment uses looser cuts for torque transmission. This segmentation resolves the contradiction by distributing different functional requirements to different spatial locations along the shaft.
Solution Approach 2:
The spiral cut pattern creates a dynamic structure that can adapt its mechanical properties. When torque is applied, the spiral cuts allow controlled deformation and energy storage, enabling the shaft to transmit torque effectively while maintaining flexibility. The dynamic interaction between the spiral cut geometry and applied forces allows the shaft to exhibit both flexibility and torque transmission capability.
3Adaptability or versatility
If a slotted or spiral cut metal shaft is used to extend flexibility limits, then the flexibility is improved, but the torque transmission and pushability deteriorate
Solution Approach 1:
The catheter shaft employs a composite construction combining a metal core with polymer coatings and spiral cut patterns. This composite structure leverages the high strength and stiffness of metal for push force transmission, while the spiral cut pattern and polymer layers provide flexibility and torque transmission. The composite design synergistically combines the advantages of different materials to resolve the contradictions between flexibility and mechanical strength.
Solution Approach 2:
The spiral cut parameters (pitch, depth, angle, width) are carefully optimized to achieve the desired balance between flexibility and mechanical strength. By adjusting these parameters, the shaft can be tuned to provide appropriate flexibility for navigation while maintaining sufficient pushability and torque transmission capability for crossing occlusions.
4Length of moving object
If small diameter polymer tubing is used to reduce profile, then the catheter size is reduced, but the pushability and risk of kinking deteriorates
Solution Approach 1:
The catheter employs a thin-walled construction with optimized wall thickness and spiral cut pattern that provides flexibility while maintaining pushability. The spiral cut pattern in the tube wall creates a flexible yet structurally sound configuration that resists kinking even in small-diameter catheters, allowing low-profile delivery without sacrificing mechanical performance.
Data Source
AI summary
A flexible, elongated catheter tube having distal and proximal ends and a laser cut section there between. The laser cut section makes up a majority of the catheter length and is cut in a continuous helical pattern forming interlocking teeth which can be sinusoidal, triangular, square or like shapes, preferably sinusoidal. The interior of the tube has a polymeric layer which forms the internal lumen of the catheter. The exterior of the tube has a polymer coating. A short portion of the distal end is uncut and is followed by a narrower terminal section which can be tapered for better blockage penetration. The interlocking teeth disengage and reengage in a fish-scale manner without undergoing plastic deformation of the metal tube and without substantial polymer separation from the tube exterior.