Pivot Thumbwheel Vascular Stent Delivery System
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Solution Overview
Problem
Pin and pull systems for deploying vascular intervention devices, such as self-expanding stents, face challenges in maintaining accurate stent positioning and control during deployment, as they require simultaneous push and pull forces, leading to potential inaccuracies and damage, especially in difficult deployments where force distribution is uneven.
Innovation Solution
A vascular intervention device delivery system with a handle featuring a pivot plate and thumbwheel mechanism that locks in one direction to prevent forward rotation, allowing tension buildup in the retractable sheath and pull mechanism in the reverse direction, enabling controlled deployment by maintaining tension and preventing slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pin and pull systems are used for stent deployment, then the stent can be deployed from a compressed state, but the user has difficulty maintaining accurate stent positioning due to simultaneous push and pull forces
Solution Approach 1:
The deployment system is segmented into distinct functional components: a fixed inner catheter that maintains position, a movable outer sheath that controls deployment, and a ratcheting mechanism that separates the pushing and pulling actions. This segmentation allows independent control of each function, eliminating the coordination difficulty of simultaneous push and pull operations.
Solution Approach 2:
A ratcheting mechanism acts as an intermediary between the user's manual operations and the sheath movement. The ratchet allows the sheath to be pulled back freely but prevents forward movement, serving as a mechanical mediator that enforces unidirectional control and eliminates the need for simultaneous bidirectional force application.
2Productivity
If high force is applied during difficult stent deployments, then the stent can be deployed, but this may lead to inaccurate positioning, shortening or lengthening, or damage to the stent or target vessel
Solution Approach 1:
The system transitions from static force application to dynamic controlled deployment. The ratcheting mechanism enables step-by-step incremental movement of the sheath, allowing the deployment process to be dynamically adjusted based on resistance forces, preventing sudden high-force applications that could damage the stent or vessel.
Solution Approach 2:
The deployment is performed through periodic incremental movements rather than continuous force application. The user pulls the sheath back in small increments, allows the stent to expand gradually, and repeats the process, creating a periodic action that distributes force over time and prevents peak forces that could cause damage.
3Productivity
If the same high force is maintained during deployment, then the stent can be deployed completely, but the stent may be deployed too fast for the user to control
Solution Approach 1:
The ratcheting mechanism enforces periodic incremental deployment rather than continuous rapid movement. Each ratchet engagement allows only a limited amount of sheath movement, creating natural deployment intervals that give the user time to control and monitor the process while still achieving complete deployment.
4Ease of operation
If the user pauses during deployment and releases built up tension, then rest can be taken, but deployment errors occur when the user resumes tension
Solution Approach 1:
The ratcheting mechanism serves as a mechanical intermediary that maintains the deployed position passively without requiring continuous user force. When the user pauses, the ratchet holds the sheath in place, preventing tension release and positioning errors. This allows the user to rest while the system maintains its state.
Data Source
AI summary
A vascular intervention device delivery system, such as for implanting a self expanding stent, includes a thumbwheel rotatably mounted in a handle. The thumbwheel includes a radially outward thumb surface and a radially outward toothed surface that may be moved into and out of contact with a catch by mounting the thumbwheel on a pivot plate within the handle. The pivot plate may be pivoted with respect to the handle between a locked position to prevent rotation of the thumbwheel, and an unlocked position that permits rotation of the thumbwheel. A catheter has a proximal end attached to the handle, and a distal carrier segment for mounting a vascular intervention device thereon. A retractable sheath is movable from a first position covering the distal carrier segment to a second position retracted proximally uncovering the distal carrier segment. A pull extends between the thumbwheel and the retractable sheath.