Variable Speed Stent Delivery via Take-Up Pulley
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Solution Overview
Problem
Current stent delivery systems face challenges in providing a variable speed deployment mechanism that allows for accurate positioning and efficient deployment of self-expanding stents within body lumens, often requiring manual force adjustments and struggling with friction issues, which can lead to inaccurate placement and increased procedural time.
Innovation Solution
A stent delivery system featuring a catheter assembly with a retractable sheath and a hand-operated deployment assembly that includes a take-up pulley and drive belt mechanism, allowing for continuously increasing deployment speed from initial to final positions, facilitating accurate and efficient stent placement by varying the retraction speed without manual position changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If manual force adjustments are used to control stent deployment speed, then the deployment can be controlled, but the operation becomes complex and time-consuming
Solution Approach 1:
The patent implements a variable speed mechanism that automatically adjusts deployment speed during stent delivery. The system transitions from slow initial deployment for positioning to faster deployment for the remaining stent length, eliminating the need for manual speed adjustments while maintaining control. This dynamic speed variation is achieved through a mechanical drive system with variable transmission ratio.
Solution Approach 2:
The deployment system is designed to automatically vary its own speed without requiring external manual intervention. The drive mechanism self-regulates the deployment rate based on the stent's position and deployment stage, reducing operational complexity while maintaining precise control over the deployment process.
2Measurement precision
If slow initial deployment speed is used for accurate positioning, then positioning precision is improved, but the overall deployment time increases
Solution Approach 1:
The patent employs periodic variation in deployment speed, using slow speed during the critical initial positioning phase and then transitioning to fast speed for the remainder of the deployment. This periodic speed adjustment ensures accurate positioning while minimizing overall deployment time by not maintaining slow speed throughout the entire process.
Solution Approach 2:
The system dynamically adjusts deployment speed based on the deployment stage, automatically transitioning from slow to fast speed. This dynamic speed control achieves both positioning accuracy during the slow phase and time efficiency during the fast phase, resolving the contradiction between precision and time.
3Productivity
If constant deployment speed is used, then the deployment process is simple, but positioning accuracy and deployment efficiency cannot be optimized simultaneously
Solution Approach 1:
The patent implements a variable speed drive mechanism that automatically adjusts deployment speed without requiring complex external control systems. The mechanical design incorporates variable transmission that provides slow speed for positioning and fast speed for deployment, achieving both efficiency and simplicity through elegant mechanical design rather than complex electronic control.
Solution Approach 2:
The patent replaces complex electronic speed control systems with a mechanically integrated variable speed drive. The drive mechanism uses mechanical means (such as differential gearing or variable pitch screw mechanisms) to automatically provide the required speed variation, simplifying the overall system while maintaining deployment efficiency and positioning accuracy.
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 enables precise and efficient deployment of stents by maintaining a slow initial speed for accurate positioning and increasing speed for rapid deployment, reducing the risk of stent dislodgment and shortening procedure time, while minimizing friction and force requirements.
Implementation Method 1
the friction between the sheath and compressed stent can be overcome in a relatively smooth or fluid manner
Data Source
Figure 1
Figure 2
Figure 3A~4B
AI summary
A handle for delivering a stent by proximal withdrawal of a sheath (262) that surrounds the stent, the handle comprising a housing (630, 634) in which is mounted a take-up pulley (656) and, proximally of the take-up pulley, an idler pulley (638), with a belt (670) for connecting to the sheath, the belt extending proximally relative to the sheath, around the idler pulley and then distally to the take-up pulley on which the belt may be wound to withdraw the sheath.