Variable-Rate Stent Deployment Line Mechanism
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Solution Overview
Problem
Existing medical device delivery systems for self-expanding stents often result in poor placement or damage to the patient's vasculature due to the stent 'jumping' or slipping during the withdrawal of the outer sheath, leading to inconsistent deployment.
Innovation Solution
A device with a deployment line that translates constant-rate actuation into variable-rate retraction, utilizing a cam device or variable pitch lead screw, to control the slow and increasing expansion of self-expanding stents, preventing slippage and ensuring accurate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outer sheath or tubular member is retracted at a constant rate, then the delivery process is simple and efficient, but the stent may jump or slip out distally of the sheath causing poor placement or damage to the patient's vasculature
Solution Approach 1:
The patent applies the dynamics principle by transitioning from constant-rate sheath retraction to variable-rate retraction. The deployment line is designed to retract at an increasing rate during the deployment process, starting slow and progressively accelerating. This dynamic retraction profile prevents the stent from jumping or slipping out distally of the sheath while maintaining delivery efficiency, thereby resolving the contradiction between delivery speed and placement accuracy.
2Productivity
If the deployment line retracts quickly to improve deployment speed, then productivity increases, but the stent placement precision deteriorates due to jumping or slippage
Solution Approach 1:
The patent implements periodic action through the staged retraction profile of the deployment line. The retraction occurs in phases: initially slow to maintain control and prevent jumping, then progressively faster to achieve complete deployment. This periodic variation in retraction rate allows the system to achieve both high deployment speed and precise stent placement by matching the retraction velocity to the stent's expansion characteristics at different stages of deployment.
Data Source
AI summary
Device useful for implanting an implantable device within the vasculature of a patient. The device includes a deployment line, a control component for actuating the deployment line, and an actuation mechanism for translating constant-rate actuation of the control component into variable rate retraction of the deployment line from a remotely deployable implantable device. Suitable implantable devices include, for example, stents and stent grafts.