Variable Stiffness Catheter Tip for Tortuous Vessel Navigation
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Solution Overview
Problem
Existing medical catheters face challenges in navigating tortuous vasculature due to rigidity and kinking issues, particularly when accessing distal tissue sites like the middle cerebral artery, which requires a balance between flexibility and structural integrity to maintain a thin profile and large inner lumen for effective delivery or removal of therapeutic agents.
Innovation Solution
The catheter design features a variable stiffness elongated body with a flexible distal portion and a stiffer proximal portion, utilizing a combination of inner liner sections with different hardness gradients and a support element like a metal braid or coil, along with an outer jacket with hardness gradients, to enhance navigability and resistance to kinking, while maintaining a thin-walled construction for large inner lumen access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the catheter uses a uniform rigid structure, then structural integrity is maintained, but navigability through tortuous vasculature deteriorates
Solution Approach 1:
The catheter is divided into multiple sections with different stiffness characteristics. The proximal portion has higher stiffness for structural integrity, while the distal portion has lower stiffness for navigability. This segmentation allows each section to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different sections of the catheter are assigned different material properties and structural characteristics. The proximal section uses stiffer materials and thicker walls for strength, while the distal section uses more flexible materials and thinner walls for ease of navigation through tortuous vessels.
2Ease of operation
If the catheter wall is made thinner to reduce profile, then navigability improves, but resistance to kinking deteriorates
Solution Approach 1:
The catheter wall thickness is segmented along its length, with thicker walls in the proximal portion for kink resistance and thinner walls in the distal portion for navigability. This gradient in wall thickness allows the catheter to maintain structural integrity where needed while being flexible where required.
Solution Approach 2:
The catheter employs local variations in wall thickness and material composition. The proximal section has thicker, stiffer walls to prevent kinking during manipulation, while the distal section has thinner, more flexible walls to navigate tortuous vasculature effectively.
3Ease of operation
If the catheter uses a uniform flexible structure, then navigability through tortuous vasculature improves, but structural integrity deteriorates
Solution Approach 1:
The catheter is segmented into proximal and distal portions with different flexibility characteristics. The proximal portion maintains higher stiffness for structural support, while the distal portion becomes progressively more flexible to navigate complex vascular pathways.
Solution Approach 2:
Different sections of the catheter have locally optimized properties: the proximal section uses stiffer materials for structural integrity during manipulation, while the distal section uses more compliant materials for effective navigation through tortuous vessels.
4Productivity
If the catheter maintains a large inner lumen for therapeutic agent delivery, then delivery effectiveness improves, but device profile increases
Solution Approach 1:
The catheter maintains a relatively large inner lumen in the distal portion for effective therapeutic agent delivery or device passage, while the proximal portion can have a smaller overall profile. This segmentation allows the catheter to be navigated through vessels and then expand or maintain its functional lumen size at the target site.
Data Source
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AI summary
In some examples, a catheter includes an elongated body comprising proximal and distal portions. The distal portion of the elongated body comprises an inner liner that includes a proximal liner section and a distal liner section that include different materials, and an outer jacket positioned over the inner liner. The distal liner section has a first hardness and the proximal liner section has a second hardness, where the first hardness is less than the second hardness.