Stent Delivery Pusher Catheter Axial Deviation Control
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Solution Overview
Problem
Existing stent delivery systems face challenges in accurately placing stents in bile ducts due to issues with axial deviation and force delivery efficiency, particularly caused by differences in wall thickness and bending stiffness between the stent and pusher catheter, leading to operational difficulties and potential stent deformation.
Innovation Solution
The stent delivery system incorporates a pusher catheter with a diameter expansion-suppressing part and an intermediate part of varying bending stiffness, designed to maintain the inner diameter of the pusher catheter and prevent axial deviation by ensuring the stent is pushed without expanding the catheter's inner diameter, while the stent and pusher catheter have similar wall thicknesses to enhance force delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pusher catheter has uniform wall thickness, then manufacturing is simple, but axial deviation occurs during stent pushing
Solution Approach 1:
The pusher catheter employs non-uniform wall thickness design where the distal end portion has a first wall thickness and the proximal end portion has a second wall thickness. This local quality variation allows the distal end to maintain smaller diameter for precise stent placement while the proximal end provides sufficient pushing force, eliminating axial deviation without complicating manufacturing.
2Force
If the pusher catheter has high bending stiffness, then force delivery is efficient, but the catheter cannot navigate curved bile ducts
Solution Approach 1:
The pusher catheter features spatially varying bending stiffness through non-uniform wall thickness distribution. The distal end with thinner wall provides flexibility for navigating curved bile ducts, while the proximal end with thicker wall delivers efficient pushing force. This local quality differentiation resolves the contradiction between navigability and force delivery.
3Force
If the pusher catheter inner diameter expands during pushing, then force transmission is improved, but stent placement precision deteriorates
Solution Approach 1:
The pusher catheter incorporates a reinforcement ring at the distal end that preliminarily counteracts the expansion tendency of the catheter wall during pushing operations. This preliminary anti-action prevents the inner diameter from expanding, thereby maintaining stent placement precision while still allowing effective force transmission through the reinforced structure.
4Force
If the pusher catheter wall is made thick, then force delivery is enhanced, but the catheter cannot pass through narrow bile duct channels
Solution Approach 1:
The pusher catheter employs local quality differentiation with variable wall thickness along its length. The distal end maintains thin wall for small outer diameter to pass through narrow bile duct channels, while the proximal end has thick wall for enhanced force delivery capability. This resolves the contradiction between force delivery and catheter size.
Data Source
AI summary
A stent delivery system includes a guide catheter, a tubular stent into which the guide catheter can be inserted, and a tubular pusher catheter into which the guide catheter can be inserted and disposed nearer to a proximal end side than the stent. The pusher catheter includes a diameter expansion-suppressing part provided at a distal end part and having the same inner diameter as the stent and an intermediate part provided at a proximal end side of the diameter expansion-suppressing part and having a bending stiffness less than that of the diameter expansion-suppressing part. When the stent is pushed toward a distal end side by pushing the intermediate part of the pusher catheter toward the distal end side and bringing a distal end part of the diameter expansion-suppressing part into contact with a proximal end part of the stent, an inner diameter of the pusher catheter is prevented from expanding.