Catheter Body Structural Support Member with Varying Stiffness
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Solution Overview
Problem
Medical catheters with uniform stiffness along their length face challenges in navigating tortuous vasculature, such as kinking and buckling, which hinders effective access to target tissue sites within the body.
Innovation Solution
A catheter design featuring a structural support member with a proximal polymer hypotube and a distal flexible support member, such as a braided or coil structure, providing varying stiffness from stiff proximal to flexible distal sections, enhancing pushability, torqueability, and flexibility for easier navigation through vasculature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a catheter has uniform stiffness along its length, then it maintains structural integrity and resistance to compression, but it experiences kinking and buckling when navigating tortuous vasculature
Solution Approach 1:
The catheter is divided into multiple segments with different stiffness characteristics: a proximal segment with higher stiffness (structural support member) and a distal segment with lower stiffness (flexible support member). This segmentation allows the catheter to maintain structural integrity in the proximal portion while enabling flexible navigation in the distal portion, resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
Different portions of the catheter are assigned different mechanical properties: the proximal portion has higher stiffness to resist compression and maintain structural integrity, while the distal portion has lower stiffness to navigate tortuous vasculature. This local differentiation of quality allows each section to perform its specific function optimally, resolving the contradiction between structural integrity and navigability.
2Strength
If a catheter has high stiffness to maintain structural integrity, then it resists compression, but it becomes difficult to manipulate and navigate through vasculature
Solution Approach 1:
The catheter structure is segmented into a proximal high-stiffness portion and a distal low-stiffness portion. The proximal segment provides compression resistance and structural support, while the distal segment provides manipulation flexibility and torqueability. This segmentation resolves the contradiction between strength and ease of operation by distributing these properties to appropriate locations.
Solution Approach 2:
The catheter exhibits local quality variations in stiffness along its length. The proximal portion has high stiffness to resist compression forces, while the distal portion has low stiffness to allow easy manipulation and torque transmission. This localized property distribution resolves the contradiction between compression resistance and manipulability.
3Ease of operation
If a catheter has low stiffness to improve flexibility, then it navigates tortuous vasculature easily, but it lacks structural integrity and resists compression poorly
Solution Approach 1:
The catheter is segmented into distal and proximal portions with different stiffness levels. The distal segment has low stiffness for flexible navigation through tortuous vasculature, while the proximal segment has high stiffness to maintain structural integrity. This segmentation resolves the contradiction between flexibility and structural integrity.
Solution Approach 2:
The catheter has locally differentiated stiffness properties: the distal portion has low stiffness to enable easy navigation through tortuous vasculature, while the proximal portion has high stiffness to maintain structural integrity. This local quality variation resolves the contradiction between navigability and reliability.
Data Source
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AI summary
A catheter body (12) includes an outer jacket (20) positioned over a structural support member (22). A proximal portion of the structural support member comprises a straight or tapered polymer hypotube (26) and a distal portion of the structural support member comprises a distal support member (28) that is more flexible than the polymer hypotube. In some examples, the polymer hypotube defines one or more openings (44) through which an adhesive may be introduced between the polymer hypotube and an inner liner (32) of the catheter body.