Balanced Pullwire Stent Delivery Catheter
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Solution Overview
Problem
Existing stent delivery systems face challenges with catheter flexibility and accuracy due to off-center guidewires or pullwires, which can cause the catheter to curve or displace during deployment, affecting the precision and effectiveness of vascular treatments.
Innovation Solution
A stent delivery system featuring a catheter with evenly spaced pullwire lumens and a pivoting connector allows for balanced pullwire movement, maintaining catheter flexibility and precision by enabling pullwires to adjust length and accommodate flexure, preventing catheter deformation and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple pullwires are held rigidly by a handle to retract the sheath, then the catheter is stabilized and prevented from curving, but the catheter becomes too stiff to be delivered to many treatment sites
Solution Approach 1:
The pullwires are made movable within the catheter body rather than being rigidly fixed, allowing the catheter to flex and adapt during delivery while maintaining stability during the retraction phase. This dynamic configuration enables the system to transition between flexibility and stability as needed.
Solution Approach 2:
The pullwire system is divided into separate movable components within the catheter body, with each pullwire able to move independently within its own lumen. This segmentation allows the catheter to maintain flexibility while the pullwires collectively provide stabilization when needed.
2Productivity
If an off-center pullwire is used to retract the sheath, then the sheath can be retracted, but the catheter turns into a curved configuration and may be displaced within the vessel
Solution Approach 1:
Multiple pullwires are positioned asymmetrically around the catheter circumference rather than using a single off-center pullwire. This asymmetric distribution of multiple pullwires balances the retraction forces and prevents the catheter from curving or displacing during sheath retraction.
Solution Approach 2:
The multiple pullwires are arranged to counterbalance each other's forces during retraction, similar to counterweights. This balanced configuration prevents the catheter from turning or displacing while still enabling effective sheath retraction.
3Ease of manufacture
If an off-center guidewire is used to guide the catheter, then the guidewire can be inserted, but the difficulty of tracking the catheter over the guidewire increases
Solution Approach 1:
The catheter is designed with multiple pullwire lumens and an enlarged proximal opening that can accommodate both on-center and off-center guidewire configurations. This universal design allows the system to work effectively regardless of guidewire positioning, maintaining ease of operation for catheter tracking.
Data Source
AI summary
In one aspect, a stent delivery system includes a catheter having two or more pullwire lumens evenly spaced about the central axis of the catheter and thereby balanced within the catheter. Pullwires are positioned in the pullwire lumens. Proximal portions of the pullwires are attached to a connector, which is attached to a master pullwire. The connector has a given range of motion that allows the pullwires to move within the pullwire lumens, thereby ensuring full flexibility of the catheter. The pullwires assume different lengths. A pullwire positioned over the outer curve of a flexed catheter may be longer than a pullwire positioned within the inner curve of the catheter, preventing the catheter from being straightened or displaced by the action of retracting the pullwires. The catheter may serve as either an inner member on which a stent is mounted or a sheath enclosing a stent.