Triple-Layer Stent Delivery System with Opposing Screw Drive
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Solution Overview
Problem
Current intravascular stent delivery systems face challenges in accurately positioning self-expandable stents due to high axial retractability and axial movement, making it difficult to implant stents with long lengths and complicating surgical procedures.
Innovation Solution
A delivery system featuring a triple-layer tube structure and a rotation driving assembly with opposing threads on the outer and intermediate screws, allowing for precise control over the stent's axial movement, enabling accurate placement and reducing operational interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional delivery system with a single tube structure is used, then the system is simple to manufacture, but it cannot accurately control the axial position of highly retractable stents during implantation
Solution Approach 1:
The delivery system is divided into three separate tube assemblies (inner tube, intermediate tube, outer tube) that can move independently relative to each other. This segmentation allows precise control of stent axial position by coordinating the movement of each tube, resolving the contradiction between positioning precision and structural simplicity.
Solution Approach 2:
The three tube assemblies are nested within each other (inner tube within intermediate tube within outer tube), creating a compact structure that maintains complexity while enabling independent axial movement of each layer. This nesting approach allows precise stent positioning without requiring a excessively complex external structure.
2Ease of operation
If the outer tube is withdrawn to deploy the stent, then the stent is released for implantation, but the high axial retractability of the stent causes it to move axially and cannot be accurately located
Solution Approach 1:
The system applies preliminary counteracting forces through the intermediate tube and inner tube to offset the axial retractability of the stent during deployment. By moving the intermediate tube in the opposite direction to the stent's retraction, the system maintains accurate axial positioning while allowing easy deployment operation.
Solution Approach 2:
The intermediate tube acts as an intermediary between the outer tube and inner tube, mediating the axial forces during stent deployment. It transmits controlled movement to counterbalance stent retraction while allowing the outer tube to be simply withdrawn for deployment, resolving the contradiction between ease of operation and positioning precision.
3Manufacturing precision
If a rotation driving assembly with opposing threads is used, then the axial retraction is effectively offset and stent implantation is precise, but the device complexity increases
Solution Approach 1:
The rotation driving assembly uses dynamic screw mechanisms with opposing threads that can be adjusted during operation to precisely control the axial movement of each tube layer. This dynamic adjustment capability provides precise stent implantation control while keeping the assembly relatively compact through the use of standard screw mechanisms.
4Adaptability or versatility
If the distal end of the inner tube passes through the stent retaining block and stent, then the system can control stent movement, but the structure becomes more complex and harder to manufacture
Solution Approach 1:
The tube assembly is segmented into three independent layers that can be manufactured separately and then assembled. This segmentation allows each tube to be manufactured using standard processes, and the complex movement control functionality is achieved through the assembly of these simpler components, resolving the contradiction between adaptability and ease of manufacture.
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
The system effectively offsets axial retraction, allowing for precise stent implantation without deformation, simplifying the surgical process and reducing the length of the handle required for operation.
Implementation Method 1
The outer screw and the intermediate screw are provided with left hand threads and right hand threads that are opposite to each other, respectively. The driving member drives the outer screw and the intermediate screw to rotate at opposite directions, and the rotation of the outer screw drives the outer screw jaw to move toward the proximal end. The rotation of the intermediate screw drives the intermediate screw jaw to move toward the distal end
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A highly retractable intravascular stent delivery system, including a tube assembly and a rotation driving assembly. The tube assembly includes an outer tube 5, an intermediate tube 6, and inner tube 7, wherein an intravascular stent 3 and a stent retaining block 4 are provided within the outer tube 5. The rotation driving assembly includes a housing 9, an outer screw 19, and an intermediate screw 14 located within the housing 9, as well as a driving member. The driving member allows two screws to rotate at opposite directions, so as to drive the outer tube 5 to move toward the proximal end, and the intermediate tube 6 pushes the stent retaining block 4 and the intravascular stent 3 to move toward the distal end. The system uses three-lay tube structure and uses driving gear to drive two screws to move at directions opposite to each other, such that the intermediate tube 6 and the outer tube 5 are driven to move to directions opposite to each other. Therefore, the axial retraction of the intravascular stents can be effectively offset and axial movement of the intravascular stents due to axial retraction of the intravascular stents is avoided, thereby accurately implanting the stents into the body.