Stent Delivery Pusher with Radial Expansion Mechanism
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Solution Overview
Problem
Medical implants such as stents often fail to be deployed in the precise position intended, making it desirable to retract them back into the delivery sheath prior to full deployment for repositioning.
Innovation Solution
A delivery system with a pusher mechanism that engages the stent's proximal loops or arms, allowing for the stent to be retracted back into its sheath using posts, channels, or retention wires, which radially expand or contract to facilitate precise positioning and repositioning of the stent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stent is deployed using a traditional pusher mechanism, then the stent can be delivered to the target location, but the stent cannot be repositioned once deployed
Solution Approach 1:
The pusher transitions from a static engagement state to a dynamic disengagement state through radial expansion of the distal end. This dynamic transformation allows the pusher to adapt its geometry - engaged with the stent during delivery, then disengaged to allow repositioning or retrieval
Solution Approach 2:
The distal end of the pusher changes its radial dimension through expansion. This parameter change transforms the pusher from a narrow profile that engages the stent to a expanded profile that releases the stent, enabling repositioning capability
2Manufacturing precision
If the pusher distal end is made rigid for precise stent positioning, then positioning accuracy is improved, but the ability to retract the stent back into the sheath is reduced
Solution Approach 1:
The pusher distal end exhibits dynamic mechanical properties - rigid during the positioning phase to ensure accuracy, then expandable to a flexible or compliant state that allows the stent to be retracted back into the delivery sheath
Solution Approach 2:
The mechanical properties of the pusher distal end are changed through radial expansion. The structure transitions from a rigid, dimensionally stable configuration for precise positioning to an expanded configuration that accommodates stent retraction
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 precise control over stent deployment and retraction, allowing for accurate placement and potential repositioning of the stent within the body, improving the accuracy of medical procedures.
Implementation Method 1
the distal end of the tubular body is heat set to radially expand when advanced out of the delivery sheath in an unconstrained position
Implementation Method 2
The posts can be pulled proximally to retrieve the stent back in to its delivery sheath prior to the stent's full deployment
Data Source
AI summary
Implant engagement mechanisms are disclosed for maintaining engagement with a stent until it has been fully deployed and expanded from a catheter or sheath. The apparatus, method and system involving these engagement mechanisms allow a physician to withdraw or retract a sheath prior to full deployment, thereby allowing for redeployment of the stent at a more desirable position.