Stent Deployment Control Member with Radially Contractible Tines
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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, which limits precise placement and retrieval within the body passage.
Innovation Solution
A control member with radially contractible and expandable tine members, formed from a cannula with slits, allows incremental movement between contracted and expanded configurations, facilitating precise positioning and recapture of stents by selectively advancing or retracting an outer cannula over the tine members, thereby controlling stent expansion and constraining its movement.
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 control member features a dynamically changeable distal end that can transition between a first configuration (engaging the stent) and a second configuration (releasing the stent). This dynamic reconfiguration allows the system to adapt its function from constraining to releasing, enabling both reliable deployment and recapture capability.
Solution Approach 2:
The control member is divided into distinct functional segments: a proximal end for actuation, a body portion, and a distal end with engageable features. The distal end can be separated or reconfigured relative to the body, allowing the engaging features to be positioned or removed from the stent engagement path, thus enabling recapture.
2Reliability
If trigger wires are used to deploy stents, then stent expansion is achieved, but inaccurate positioning and foreshortening occur
Solution Approach 1:
The control member's distal end can dynamically change configuration to provide controlled expansion rather than abrupt full expansion. This allows incremental positioning adjustments and reduces foreshortening by maintaining longitudinal constraint during the expansion process.
Solution Approach 2:
The control member is designed to maintain the stent in a constrained, pre-deployment configuration during delivery and positioning. The engaging features at the distal end hold the stent in place before expansion, allowing precise positioning to be achieved before the expansion action occurs.
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 enables improved positioning and recapture of stents within the body passage, reducing undesirable foreshortening and enhancing deployment accuracy, allowing for controlled incremental expansion and contraction of stents, including stent-grafts and other implantable medical devices.
Implementation Method 1
If a control member is formed from a shape memory material, then selective actuation of the control member may permit at least partial radial expansion of a stent within a body passage, and also may permit at least partial radial contraction of the stent to permit repositioning of the stent within the body passage
Data Source
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AI summary
Apparatus for facilitating deployment of a an implantable medical device includes a control member (20) having at least one tine member (35-37). A proximal region (35b-37b) of at least one of the tine members (35-37) is configured to engage an associated portion of a stent (60). In use, the control member (20) comprises a contracted delivery configuration m which the proximal region of the at least one of the tine member (35-37) is radially contracted, to radially constrain the associated portion of the stent (60). The control member (20) also comprises an expanded configuration in which the proximal region of the at least one of the tine member (35-37) expands radially outward relative to the central longitudinal axis to allow the stent to engage a body passage. The proximal region of the at least one tine member (35-37) is selectively movable an incremental amount between the contracted and expanded configurations, in radially inward and outward directions, to facilitate positioning of the stent (60) within the body passage.