Stent Delivery Sheath Rack Mechanism for Low-Force Retraction
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Solution Overview
Problem
Existing stent delivery systems face challenges in efficiently deploying stents while maintaining guidewire position and reducing kinking, particularly in tortuous anatomies, and there is a need for alternative manufacturing methods and designs to enhance deployment mechanisms.
Innovation Solution
A stent delivery system featuring a deployment sheath coupled to a flexible rack with a rotatable linkage and a toothed section that engages a gear within a handle, allowing for precise control and reduced force requirements during stent deployment, along with a coupling member to facilitate rotation and prevent distal translation, and a sleeve to limit distal movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional stent delivery system is used, then the stent can be delivered to the target location, but high force is required to retract the deployment sheath and maintain guidewire position
Solution Approach 1:
The patent replaces the traditional mechanical rack-and-pinion system with a flexible rack that can bend and conform to the curvature of the delivery catheter. This flexible rack engages with a gear on the deployment hub, creating a mechanical advantage that reduces the force required to retract the deployment sheath. The flexible nature of the rack allows it to navigate tortuous anatomies while maintaining effective force transmission.
Solution Approach 2:
The deployment sheath and flexible rack system allows for dynamic adjustment during the deployment process. The flexible rack can adapt its configuration based on the curvature of the delivery system, optimizing force transmission at different stages of sheath retraction. This dynamic adaptation reduces the overall force requirement compared to rigid systems.
2Stability of the object's composition
If a rigid delivery system is used, then structural stability is maintained, but kinking occurs in tortuous anatomies
Solution Approach 1:
The patent employs a flexible rack made from a compliant material that can bend and conform to the curvature of the delivery catheter and tortuous anatomies. This flexible component maintains the necessary structural stability for force transmission while adapting to the curved path, preventing kinking that would occur with rigid components.
Solution Approach 2:
The delivery system is divided into segments with different flexibility characteristics. The flexible rack is segmented along its length, with varying degrees of compliance allowed. This segmentation enables the system to maintain stability in straight sections while flexing in curved sections, preventing kinking in tortuous anatomies.
3Measurement precision
If a complex deployment mechanism is used, then precise control is achieved, but device complexity increases
Solution Approach 1:
The flexible rack serves multiple functions: it transmits force from the deployment hub to the deployment sheath, maintains guidewire position, and adapts to the curvature of the delivery system. This multi-functionality reduces the need for separate components, simplifying the overall device while maintaining precise control over stent deployment.
Solution Approach 2:
The flexible rack acts as an intermediary between the deployment hub and the deployment sheath. It translates the rotational motion of the deployment hub into linear retraction of the sheath, providing precise control while simplifying the mechanical interface. The flexible nature of the rack mediates between the rigid components, reducing complexity.
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
Enhances stent deployment efficiency by reducing the force needed to retract the deployment sheath, maintaining guidewire position, and minimizing kinking, thereby improving procedural ease and safety.
Implementation Method 1
a toothed section that engages a gear within a handle
Implementation Method 2
a flexible rack with a rotatable linkage and a toothed section that engages a gear within a handle
Implementation Method 3
a flexible rack with a rotatable linkage and a toothed section
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Stent delivery systems and methods for making and using stent delivery systems are disclosed. An example stent delivery system may include an inner member having a stent receiving region. A stent may be disposed along the stent receiving region. The system may also include a deployment sheath axially slidable relative to the inner member. The deployment sheath may have a proximal end region. A rack may be coupled to the proximal end region of the deployment sheath. An outer shaft may be disposed along at least a portion of the deployment sheath. The deployment sheath may be rotatable relative to the inner member, the outer shaft or both.