Stent Introducer Axial Force Management
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Solution Overview
Problem
Conventional stent delivery systems face challenges such as difficulty in repositioning or removing the stent after deployment, inaccurate placement due to sheath obstruction, high force requirements for stent deployment, and mechanical alterations during extended compression, which affect the stent's mechanical properties and increase the risk of malfunction.
Innovation Solution
A stent delivery system with an elongate shaft and constraining members that allow for controlled deployment and repositioning of the stent, featuring a proximal and distal constraining mechanism with a restraining member to manage axial force and facilitate uniform expansion, enabling precise placement and retraction of the stent within the body lumen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional outer sheath/inner catheter delivery device is used, then the stent can be delivered and deployed, but the device is difficult to reposition or remove and slow to operate
Solution Approach 1:
The delivery device is divided into separate functional components: an outer introducer sheath, an inner catheter, and a stent. The stent is segmented into a distal portion and a proximal portion that can be deployed independently through separate release mechanisms, allowing for controlled repositioning and removal if needed.
Solution Approach 2:
The delivery system incorporates dynamic elements including a movable outer sheath that can be retracted, a deployable inner catheter, and a stent that can transition between compressed and expanded states. The release wires and constraining members allow for dynamic control of the deployment process, enabling repositioning before final deployment.
2Manufacturing precision
If the outer sheath is proximally withdrawn to deploy the stent, then the stent can be expanded, but accurate placement of the proximal portion is difficult
Solution Approach 1:
The stent is pre-positioned within the delivery device with the distal portion first, allowing for preliminary placement and verification of position. The proximal portion remains constrained during this initial placement phase, enabling accurate positioning before complete deployment.
Solution Approach 2:
The stent deployment is segmented into two phases: first the distal portion is released and positioned, then the proximal portion is released. This sequential release allows for precise control of stent placement and ensures accurate positioning of both ends of the stent within the body lumen.
3Measurement precision
If direct visualization of the stent is required for accurate placement, then placement accuracy improves, but the sheath obscures the stent location
Solution Approach 1:
The stent and delivery device components are designed with radiopaque materials that appear distinct under imaging guidance. The stent has different radiopaque characteristics than the delivery device, allowing for clear visualization and differentiation during the placement procedure.
Solution Approach 2:
Radiopaque markers and imaging guidance serve as intermediaries between the physician and the stent location. These markers provide visual information about stent position without requiring direct line of sight, overcoming the obstruction caused by the sheath.
4Force
If high force is applied to overcome friction between stent and sheath, then the stent can be deployed, but stretching of the introducer and hysterics in stent movement occur
Solution Approach 1:
The delivery system incorporates a balloon that can be inflated to provide controlled radial force for stent deployment. This pneumatic mechanism distributes the deployment force uniformly, reducing peak forces and preventing stretching or erratic movement of the stent and introducer.
Solution Approach 2:
The system changes the deployment parameter from pure mechanical pulling force to controlled balloon inflation pressure. This parameter change allows for more uniform and controlled force application, reducing the risk of device stretching and stent movement irregularities.
5Ease of manufacture
If the stent is compressed for extended periods during shipping and storage, then the stent can be delivered, but mechanical alterations occur that affect stent properties
Solution Approach 1:
The stent is pre-compressed to a specific configuration for delivery, but this compression is maintained only for the minimal necessary time during the procedure. The design allows for rapid deployment, minimizing the duration of compression and reducing mechanical alterations to the stent material.
Solution Approach 2:
The compression parameters (force, duration, temperature) are optimized to balance deliverability with material stability. The stent is designed with material properties and structural features that resist permanent deformation during the brief compression period required for delivery.
Data Source
AI summary
A stent delivery system and method are provided. The stent delivery system includes an elongate shaft including a proximal portion, a distal portion, at least one lumen extending at least partially therethrough, and a stent receiving portion on the distal portion of the elongate shaft. A stent is positioned on the stent receiving portion of the elongate shaft, the stent having a first position and a second position. A proximal constraining member is positioned on a proximal end of the stent. A distal constraining member is positioned on a distal end of the stent. A restraining member disposed throughout a length of the elongate shaft and releasably engaged with at least one of the proximal constraining member and the distal constraining member, the restraining member having a proximal end and a distal end. The stent is in the first position, the distal restraining member applies an axial mechanical force to the distal constraining member.