Catheter Tip Assembly Snag Prevention
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Solution Overview
Problem
Conventional stent delivery systems face issues with the catheter tip snagging on the stent during withdrawal, leading to potential dislodgment and inaccurate deployment due to the formation of gaps and edges that catch on the stent, causing delays and inaccuracy in placement.
Innovation Solution
A catheter tip assembly with a tapered proximal end, elongate center portion, and tapered distal end, where the inner catheter flares outwardly to form a wide distal end with a larger inner diameter, eliminating the proximal-facing edge that can catch on the stent, and a stop member is used to prevent the stent from moving with the outer catheter, ensuring precise deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional catheter tip with a straight juncture is used, then the structure is simple and easy to manufacture, but the catheter tip forms a proximal-facing edge that snags on the stent during withdrawal
Solution Approach 1:
The catheter tip is designed with a curved profile consisting of a first curved portion and a second curved portion that meet at a juncture. This curvature eliminates the sharp proximal-facing edge found in conventional straight catheter tips, allowing the catheter to smoothly pass through the stent lumen during withdrawal without snagging. The curved geometry transforms the problematic sharp edge into a gradual transition that prevents catching on the stent structure.
2Manufacturing precision
If the inner catheter has a uniform diameter, then the structure is simple, but gaps form between the catheter tip and inner catheter allowing the stent to move with the outer catheter
Solution Approach 1:
The inner catheter is designed with non-uniform diameter, featuring a distal portion with a larger diameter than the proximal portion. This local variation in diameter creates an interference fit between the inner catheter and the catheter tip at the distal end, preventing gaps from forming. The larger distal diameter of the inner catheter ensures tight engagement with the catheter tip, thereby preventing the stent from moving axially with the outer catheter during deployment while maintaining overall structural simplicity.
3Reliability
If the catheter tip is directly attached to the inner catheter with uniform diameter, then the structure is simple, but the stent can move axially with the outer catheter during withdrawal
Solution Approach 1:
The inner catheter features a localized diameter variation with a larger distal portion that creates an interference fit with the catheter tip. This local geometric feature prevents axial movement of the stent by ensuring tight engagement between the catheter components at the critical distal interface, while the rest of the catheter structure remains relatively simple.
Solution Approach 2:
The curved profile of the catheter tip, with its first and second curved portions meeting at a juncture, works in conjunction with the inner catheter's diameter variation to prevent stent dislodgment. The curved geometry ensures smooth engagement and prevents sharp edges from catching on the stent, while the diameter variation provides the necessary mechanical constraint against axial movement.
Data Source
AI summary
A catheter tip assembly (50) is provided with a catheter tip (56) and an inner catheter (54). The catheter tip (56) has a tapered proximal end, an elongate center portion, and a tapered distal end. The inner catheter (54) includes a narrow proximal portion, a narrow elongate center portion (66), and a wide distal end (68). The catheter tip (56) is disposed within the wide distal end (68) of the inner catheter (54). One advantage of the catheter tip assembly is that no proximal-facing edge is formed at the transition between the narrow elongate center portion of the inner catheter and the catheter tip, which may help reduce the risk of the catheter tip snagging on a stent during use.