Stent Delivery Device Anchorage System
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Solution Overview
Problem
Existing stent delivery devices face challenges in reducing deployment force, particularly with longer stent devices, while maintaining deployment accuracy, as the friction between the outer sheath and stent can cause structural damage and compromise precision.
Innovation Solution
The delivery device employs a unique anchorage system with annular rings at the distal portion and a proximal stop to limit axial movement, allowing the remaining portion of the stent to move with the outer sheath, thereby reducing frictional forces and deployment force, while ensuring accurate deployment by distributing the force effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a proximal stop abutting a proximal end of the stent device is used to hold the stent axially, then the stent can be held in position during outer sheath retraction, but the friction between the outer sheath and stent causes foreshortening of the stent and compromises deployment accuracy
Solution Approach 1:
The invention extracts the anchoring function from the proximal end of the stent and relocates it to the distal end. The distal portion of the stent engages with the inner catheter while the remaining portion is free to move with the outer sheath during retraction, eliminating the harmful friction at the proximal end that caused foreshortening and deployment inaccuracies.
Solution Approach 2:
Instead of anchoring the proximal end of the stent to the inner catheter (conventional approach), the invention anchors the distal portion of the stent to the inner catheter. This inversion allows the outer sheath to retract smoothly over the remaining portion without causing axial compression or foreshortening of the stent.
2Reliability
If the outer sheath is dragged over the stent device during retraction, then the stent can be held axially by friction, but the deployment force increases and can damage the stent structure
Solution Approach 1:
The invention removes the stent from the path of the retracting outer sheath by anchoring only the distal portion to the inner catheter. The remaining portion moves freely with the outer sheath, eliminating the frictional forces that could damage the stent structure during deployment.
Solution Approach 2:
The stent is functionally segmented into two portions: a distal portion that remains anchored to the inner catheter and a remaining portion that moves with the outer sheath. This segmentation allows the outer sheath to retract without dragging over the entire stent length, reducing deployment forces and preventing structural damage.
3Reliability
If a continuous high friction sleeve is used to hold the stent axially, then the deployment force increases due to the sleeve forcing the stent into the outer sheath, but the force is evenly distributed
Solution Approach 1:
The invention eliminates the continuous high friction sleeve and instead uses discrete anchoring elements (such as ridges or engagement features) on the inner catheter that engage with the distal portion of the stent. This allows the remaining portion of the stent to move freely with the outer sheath during retraction, dramatically reducing the deployment force required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces the deployment force required to retract the outer sheath, minimizing the risk of stent damage and enhancing deployment accuracy, especially for longer stent devices, by limiting frictional forces and allowing the stent to expand radially without compromising its integrity.
Implementation Method 1
The stent device is made of a shape memory material and will maintain its reduced profile configuration when below a transition temperature. Once the transition temperature is breached, the stent device will tend to return to its expanded profile, deployed configuration for holding open the bodily lumen.
Implementation Method 2
There is friction between an outer sheath and a stent device as the outer sheath is dragged over the outer surface of the stent device during retraction for deployment.
Data Source
Figure 1
AI summary
A delivery device for delivering a stent device in a reduced profiled delivery configuration is provided. A distal region of the stent device is axially anchored to an inner catheter by annular rings about the inner catheter. A remaining portion of the stent device is spaced radially from the inner catheter. A proximal stop is spaced axially from a proximal end of the stent device. The stent device is maintained in the reduced profile delivery configuration by a retractable cuter sheath.