Stent Deployment Trigger Wire Recapture Mechanism
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Solution Overview
Problem
Conventional stent deployment methods using trigger wires often result in inaccurate positioning and difficulty in recapturing or repositioning stents due to full radial expansion and foreshortening issues.
Innovation Solution
A system comprising an inner cannula with a trigger wire extending partially within its lumen and an outer cannula for controlled longitudinal movement, allowing partial deployment and incremental radial constriction of the stent, enabling improved positioning and recapture of stents within a body passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trigger wires are used to deploy stents, then full radial expansion of the stent is achieved, but the stent becomes difficult or impossible to recapture or reposition
Solution Approach 1:
The delivery system employs dynamic control through dual-cannula interaction with the trigger wire. The outer cannula can be selectively retracted to allow stent expansion while the inner cannula maintains engagement with the trigger wire, enabling transition from a constrained to an expanded state with controlled recapturability throughout the deployment process.
Solution Approach 2:
The system changes the mechanical parameters of stent deployment by controlling the interaction between the inner and outer cannulas. By adjusting the relative positions and engagement forces of the cannulas with the trigger wire, the stent can be deployed incrementally rather than fully expanded at once, maintaining recapturability during the transition.
2Reliability
If trigger wires are used to deploy stents, then the stent engages the body passage, but inaccurate positioning occurs due to foreshortening
Solution Approach 1:
The system performs preliminary positioning adjustments by controlling the outer cannula's retraction timing and extent. This allows the operator to establish accurate stent positioning before final deployment, compensating for potential foreshortening effects that occur during expansion.
Solution Approach 2:
The dual-cannula mechanism provides mechanical feedback control during deployment. The inner cannula's engagement with the trigger wire and the outer cannula's interaction with the trigger wire create a controlled system that responds to deployment forces, allowing real-time adjustment of stent position to maintain accuracy.
3Device complexity
If conventional trigger wire actuation is used, then stent deployment is simplified, but the stent foreshortens or moves an undesired amount
Solution Approach 1:
The deployment mechanism is segmented into two independent cannulas (inner and outer) that can be controlled separately. This segmentation allows independent control of the deployment process, enabling the operator to manage stent expansion and positioning independently to prevent unwanted foreshortening while maintaining operational simplicity.
Solution Approach 2:
The inner cannula acts as an intermediary between the operator and the trigger wire, while the outer cannula serves as an additional control layer. This intermediary mechanism distributes the deployment control functions, allowing precise management of stent longitudinal position during expansion without complicating the overall deployment process.
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
This approach facilitates precise positioning and recapture of stents, reducing undesirable foreshortening and enhancing deployment accuracy, allowing for controlled expansion and contraction of stents.
Implementation Method 1
Selective proximal advancement of the outer cannula over the exposed portion of the at least one trigger wire incrementally urges the exposed portion of the at least one trigger wire in a radially inward direction to radially constrain the associated portion of the stent
Implementation Method 2
In a stent made of a shape-memory alloy such as nitinol, the shape-memory alloy may be employed to cause the stent to return to a predetermined configuration upon removal of the sheath or other device maintaining the stent in its predeployment configuration
Implementation Method 3
the stent expand primarily based on their own expansive force without the need for further mechanical expansion
Data Source
AI summary
The present embodiments provide systems and methods for facilitating deployment of a stent. In one embodiment, the system comprises an inner cannula, and at least one trigger wire extends at least partially within a lumen of the inner cannula and has an exposed portion extending radially outside of the lumen of the inner cannula. The exposed portion of the at least one trigger wire engages an associated portion of a stent in a delivery state. An outer cannula is sized for longitudinal movement over a portion of the inner cannula. Selective distal retraction of the outer cannula permits partial deployment of the stent to an extent of slack provided by the at least one trigger wire, and selective proximal advancement of the outer cannula incrementally urges the exposed portion of the at least one trigger wire radially inward to constrain the associated portion of the stent.