Longitudinally Folded Stent with Trigger Wire Constraint
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Solution Overview
Problem
Current stent construction methods, particularly for micro-vascular anastomosis, face challenges in efficiently connecting small blood vessels due to the creation of large, rigid couplings and time-consuming manual suturing, which complicates the process of end-to-end anastomosis in reconstructive or transplant surgeries.
Innovation Solution
A stent assembly with a tubular rest shape and a trigger wire mechanism that constrains the stent in a folded configuration, allowing it to be slid into vessels and then resiliently unfold into a larger diameter for secure connection, using a framework that can be cut from a cannula or made from super-elastic materials, with the trigger wire applying a shear force to maintain the folded shape until deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the stent is constructed with interconnected struts and reduced vertex angles for delivery, then the stent can be delivered in a small diameter configuration, but the stent creates large rigid couplings that complicate micro-vascular anastomosis
Solution Approach 1:
The stent is divided into multiple individual struts that can be independently positioned and interconnected. Each strut acts as a separate element that can be precisely controlled during deployment, allowing the stent to achieve its expanded configuration without creating large rigid couplings. The struts are connected through simple joint mechanisms rather than complex rigid structures.
Solution Approach 2:
The stent struts are designed to nest within each other during the delivery phase, allowing the entire stent structure to be compressed into a small delivery profile. Upon deployment, the nested struts unfold and interconnect to form the expanded stent structure, avoiding the need for complex coupling mechanisms.
2Reliability
If manual suturing is used for micro-vascular anastomosis, then vessels can be connected, but the procedure becomes time consuming and difficult
Solution Approach 1:
The stent is designed to self-deploy and self-secure upon release from the delivery catheter. The struts automatically unfold and interconnect to form a stable structure that holds the vessels together, eliminating the need for time-consuming manual suturing while maintaining reliable vessel connection.
Solution Approach 2:
The stent is pre-formed with the complete strut structure during manufacturing. Before deployment, the entire stent is crimped onto the delivery catheter in its compressed state. Upon release, the pre-formed structure automatically expands into position, performing the vessel connection function without requiring time-consuming intra-procedural assembly or suturing.
3Shape
If the stent framework is made resilient to unfold, then the stent can expand to a larger diameter for implantation, but a trigger wire is needed to constrain the folded shape during delivery
Solution Approach 1:
The trigger wire serves as an intermediary constraint mechanism that temporarily holds the stent in its compressed delivery configuration. The wire is inserted through the delivery catheter and engages with the stent struts to prevent premature expansion. Upon release, the trigger wire is withdrawn, allowing the resilient stent framework to automatically unfold to its expanded implantation diameter without requiring complex deployment mechanisms.
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
Facilitates efficient and minimally invasive end-to-end anastomosis by allowing the stent to expand from a small, maneuverable profile to a larger diameter within the vessels, reducing procedural time and minimizing tissue damage, while maintaining a secure connection.
Implementation Method 1
The framework has a folded shape with a cross section perpendicular to the longitudinal axis that fits within a closed shape having a perimeter that is smaller than the expanded perimeter. The stent assembly has a constrained configuration characterized by the framework being held in the folded shape by the trigger wire being in contact with at least one of the internal surface and the external surface to apply a shear force perpendicular to the longitudinal axis responsive to a bias of the framework to resiliently unfold.
Implementation Method 2
The stent assembly has an unconstrained configuration characterized by the framework being in the tubular rest shape with the trigger wire out of contact with the framework
Data Source
AI summary
A stent assembly includes a framework having a tubular rest shape that defines a longitudinal axis, has an external surface that defines an expanded perimeter, and an internal surface that defines a passageway. The framework has a folded shape with a cross section perpendicular to the longitudinal axis that fits in a closed shape having a perimeter that is smaller than the expanded perimeter. The stent assembly has a constrained configuration characterized by the framework being held in the folded shape by a trigger wire supporting sheer stress by being in contact with interlaced loops of the framework. The stent assembly has an unconstrained configuration characterized by the framework being in the tubular rest shape with the trigger wire out of contact with the framework.