Reconstrainable Stent Delivery System With Suture Retrieval
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Solution Overview
Problem
Conventional sheath-based stent delivery systems face challenges such as difficulty in repositioning or removing self-expanding stents due to radial expansion, foreshortening, and obstruction during visualization, requiring high force for deployment, and increased complexity and cost.
Innovation Solution
A stent delivery system that allows for the stent to be expanded or partially expanded for deployment and later reconstrained for repositioning or removal, utilizing a suture and grasping loop mechanism to facilitate precise placement and retrieval, eliminating the need for stent lock wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sheath-based delivery system is used, then the stent can be delivered through the body lumen, but the stent cannot be repositioned or removed after deployment due to radial expansion
Solution Approach 1:
The stent delivery system transitions from a static constrained state to a dynamic deployable state. The self-expanding stent is initially constrained within the delivery catheter, then dynamically expands when released. The system allows reversible constrainment during deployment, enabling the stent to transition between compressed and expanded states for repositioning if needed.
Solution Approach 2:
The stent is pre-loaded into the delivery catheter in a compressed state before use. The delivery system is prepared in advance with the stent securely positioned within the catheter lumen, allowing controlled deployment when needed. The proximal portion of the stent is pre-positioned to engage with the delivery system for subsequent repositioning operations.
2Manufacturing precision
If the outer sheath is proximally withdrawn to deploy the stent, then the stent expands, but the proximal portion of the stent cannot be accurately placed due to foreshortening
Solution Approach 1:
The delivery catheter acts as an intermediary between the operator and the stent. It provides a controlled environment for stent deployment, allowing the stent to expand gradually as the catheter is withdrawn. The catheter's structured opening at its distal end guides the stent's expansion and positioning, ensuring accurate placement despite foreshortening effects.
Solution Approach 2:
The proximal portion of the stent is pre-positioned within the delivery catheter to engage with the catheter's structured opening. This preliminary positioning ensures that when the stent expands, the proximal portion maintains accurate alignment and placement, compensating for foreshortening that occurs during expansion.
3Measurement precision
If direct visualization of the stent is required for accurate placement, then the sheath obscures the stent location, but without a sheath the stent cannot be controlled during delivery
Solution Approach 1:
The delivery catheter is constructed with flexible materials that allow it to be thin-walled yet structurally sound. The catheter wall is sufficiently transparent or radiopaque to allow visualization of the stent within, while maintaining the structural integrity needed to control and constrain the stent during delivery through the body lumen.
Solution Approach 2:
The delivery catheter features a structured opening at its distal end that is segmented or configured to allow selective visualization. This segmentation enables the stent to be visualized through the catheter wall and opening while the catheter maintains its constraining function, resolving the conflict between visibility and control.
4Productivity
If high force is applied to overcome friction between the stent and sheath, then the stent can be deployed, but the introducer catheter may stretch or experience hysteresis
Solution Approach 1:
The system replaces high-force mechanical extraction with a controlled expansion mechanism. Instead of pulling the stent through the catheter with high force, the stent is allowed to self-expand as the catheter is gently withdrawn. This substitution of expansion for extraction reduces frictional forces and protects the introducer catheter from stretching and hysteresis.
Solution Approach 2:
The deployment process is made dynamic and gradual rather than forceful. The stent expands progressively as the delivery catheter is withdrawn, converting a high-force static extraction problem into a low-force dynamic expansion process. This reduces frictional consequences and protects the catheter structure.
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
Enables accurate and efficient stent placement, reduces trauma to surrounding tissue, and simplifies the stent delivery process by allowing for repositioning and removal without the need for stent lock wires, improving the overall efficiency and accuracy of stent deployment.
Implementation Method 1
Self expanding stents are useful for a variety of procedures requiring the maintenance of the patency of a bodily pathway. Such stents are generally biased to expand, such that when deployed, they assume an open position, pushing outward and into the surrounding area into which deployed.
Implementation Method 2
Self expanding stents are generally biased to expand, such that when deployed, they assume an open position
Implementation Method 3
Self expanding stents are generally biased to expand
Data Source
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AI summary
A system (100) for the delivery and repositioning of a stent (102) is provided that allows the stent to be reconstrained after full or partial expansion for deployment to and removal from a target region.