Stent Delivery Control System Using Pressure-Driven Shaft Actuation
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Solution Overview
Problem
Conventional sheathed stent delivery systems face challenges such as difficulty in repositioning or removing the stent, inaccurate placement due to premature deployment, obstruction during direct visualization, high force requirements for stent placement, and increased complexity and cost, which are addressed by developing a longitudinally tensioned stent delivery system with a control mechanism for precise stent deployment and reconstriction.
Innovation Solution
A control system comprising a housing with a chamber, first and second drives connected to inner and outer shafts, and a pressure controller to manage pressure changes within the chamber, allowing for precise movement of the shafts to expand or constrain the stent, enabling controlled deployment and reconstriction of the stent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional outer sheath/inner catheter delivery device is used to deliver a self-expanding stent, then the stent can be delivered to the target site, but the device becomes difficult to reposition or remove and slow to operate once the stent is deployed
Solution Approach 1:
The delivery device employs dynamic control mechanisms including a deployable anchor system and adjustable outer sheath positioning that allow the device to transition between different operational states. The anchor can be deployed to secure the device in place during stent deployment, then retracted to enable repositioning if needed, providing adaptive control throughout the procedure.
Solution Approach 2:
The device utilizes controlled changes in the radial and longitudinal parameters of the outer sheath and inner catheter to manage stent deployment. By precisely controlling the expansion ratio and positioning of these components, the device enables accurate stent placement while maintaining the capability to retract or reposition before full deployment occurs.
2Measurement precision
If the outer sheath is proximally withdrawn to deploy the stent, then the stent expands from distal end to proximal end, but the physician cannot accurately place the proximal portion of the stent and direct visualization is obstructed
Solution Approach 1:
The device incorporates an inner catheter that acts as an intermediary structure, allowing the outer sheath to be withdrawn while maintaining a visible reference framework. The inner catheter remains in place during sheath retraction, providing a visual guide that enables the physician to track stent deployment progress and accurately position both the proximal and distal portions of the stent.
Solution Approach 2:
The delivery system utilizes a coaxial arrangement where the inner catheter and outer sheath operate in different dimensional spaces. The inner catheter provides a longitudinal reference axis that remains visible during the radial expansion process, allowing visualization along the length of the stent deployment without being obstructed by the retracting outer sheath.
3Force
If a conventional sheathed delivery device is used, then the stent can be compressed and delivered, but high force is required to overcome friction between the stent and sheath
Solution Approach 1:
The device extracts the stent from the outer sheath in a controlled manner during deployment. By separating the stent delivery function from the outer sheath constraint, the system reduces the frictional interface between stent and sheath, requiring less force for stent placement while maintaining delivery capability.
Solution Approach 2:
The device replaces pure mechanical friction-based delivery with a controlled expansion mechanism. Instead of relying on force to push the stent through the sheath, the system uses controlled radial expansion of the inner catheter and coordinated retraction of the outer sheath to minimize friction and enable smoother stent deployment with reduced force requirements.
4Reliability
If the stent is fully deployed before repositioning attempts, then the stent is securely in place, but the sheath cannot reconstrain the stent for repositioning
Solution Approach 1:
The device performs preliminary actions by deploying the anchor and positioning the outer sheath and inner catheter in specific configurations before stent deployment. These preliminary positioning steps create a controllable state where the stent can be deployed with confidence while maintaining the mechanical capability to retract components for repositioning if the placement is not optimal.
Solution Approach 2:
The delivery system employs dynamic component interaction where the outer sheath and inner catheter can be independently adjusted during the deployment process. This dynamic control allows the system to transition from a constrained delivery state to a deployed state while maintaining the option to reverse or adjust positioning before final stent expansion is complete.
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 control system enhances the accuracy and ease of stent placement, allows for precise control over stent deployment and reconstriction, and reduces the complexity and cost associated with conventional sheathed systems, improving the overall stent delivery process.
Implementation Method 1
a pressure controller operably connected to the housing and configured to change the pressure within the chamber. The first drive and the second drives are movable in response to the pressure change within the chamber
Data Source
AI summary
A control system for controlling movement of a stent delivery system, a stent delivery system and a method for controlling movement of a stent delivery system are provided. The control system includes a housing having a chamber formed therein, a first drive at least partially positioned within the housing and operably connected to the first shaft of the delivery system and a second drive at least partially positioned within the housing and operably connected to the second shaft. The control system also includes a pressure controller operably connected to the housing and configured to change the pressure within the chamber. The first drive and the second drives are movable in response to the pressure change within the chamber and movement of the second drive relative to the first drive causes the second shaft to move relative to the first shaft to expand or constrain a stent operably connected thereto.