Two-Stage Stent Deployment Handle for Sheath Friction Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of retracting a sheath from an expandable medical device, such as a stent, is often hindered by significant static friction, making it difficult to achieve controlled and steady deployment.
Innovation Solution
A handle with a two-stage deployment mechanism, involving a lever and carriage, first rotates the lever to overcome initial friction and then slides it proximally to fully retract the sheath, providing mechanical advantage and controlled exposure of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-stage sheath retraction mechanism is used, then the deployment process is simple, but static friction prevents controlled and steady deployment
Solution Approach 1:
The deployment mechanism is divided into two distinct stages: a first stage with a first lever for initial sheath retraction, and a second stage with a second lever for complete device exposure. This segmentation allows each stage to be optimized independently - the first stage overcomes static friction with mechanical advantage, while the second stage completes the deployment, thereby resolving the contradiction between controlled operation and device complexity.
2Reliability
If mechanical advantage is provided to overcome static friction, then controlled retraction is achieved, but the deployment mechanism becomes more complex
Solution Approach 1:
The mechanism transitions from a static single-lever design to a dynamic two-stage system where the first lever provides mechanical advantage specifically when needed to overcome static friction during initial retraction, then disengages to allow the second lever to complete the motion. This dynamic adaptation provides reliable controlled retraction only when necessary, reducing overall complexity.
3Productivity
If the sheath is retracted quickly to deploy the device, then productivity is improved, but control and precision are lost
Solution Approach 1:
The deployment process is structured as periodic action with two distinct phases: the first lever provides controlled initial retraction to overcome friction, then the second lever completes the retraction for rapid device exposure. This periodic two-stage action achieves both productivity (fast complete deployment) and precision (controlled initial phase), resolving the contradiction between speed and control.
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 two-stage process effectively manages static friction, ensuring the expandable device is exposed in a controlled and steady manner, facilitating precise deployment.
Implementation Method 1
The challenge of retracting a sheath from an expandable medical device, such as a stent, is often hindered by significant static friction
Implementation Method 2
The two-stage process effectively manages static friction, ensuring the expandable device is exposed in a controlled and steady manner
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus (22) for retracting a sheath (24) from over an expandable medical device (38) includes a shell (44), configured to couple to a longitudinal element (26), a carriage (48) disposed within the shell and configured to couple to the sheath, and a lever (40) protruding from the shell. The lever is configured to retract the sheath while a distal end of the longitudinal element contacts the expandable medical device, by rotating proximally so as to move the carriage proximally by a first distance, and, subsequently to rotating proximally, sliding proximally so as to move the carriage proximally by a second distance. Other embodiments are also described.