Sheath Interface Sleeve for Medical Delivery Friction Reduction
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Solution Overview
Problem
Current delivery systems for implantable medical devices, such as prosthetic heart valves and stents, face challenges with frictional resistance and displacement issues during the transluminal insertion procedure due to the difference in diameters between the outer and inner shafts, which impede precise positioning and deployment of the device.
Innovation Solution
A delivery device design featuring an elongated inner shaft with a device-carrying region, a hollow outer shaft with a slideable sheath, and a sleeve that surrounds the outer shaft, allowing for smooth transition and reduced friction, enabling precise positioning and deployment of the implantable device by accommodating different diameters and minimizing displacement during the procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the outer shaft has a smaller diameter than the sheath to provide flexibility, then the delivery system can bend to follow the guidewire path, but friction between the seal and outer shaft impedes advancing motion and causes displacement during device exposure
Solution Approach 1:
A lubricious coating is applied to the outer shaft surface to act as an intermediary layer between the outer shaft and the elastomeric seal. This coating reduces the coefficient of friction, allowing the outer shaft to slide more smoothly through the seal during advancement and device exposure, thereby reducing displacement while maintaining the necessary flexibility of the smaller-diameter outer shaft
2Adaptability or versatility
If the outer shaft diameter is reduced for flexibility, then the delivery system can navigate tortuous vasculature, but the friction between the seal and outer shaft increases, impeding motion and causing handle displacement
Solution Approach 1:
The surface properties of the outer shaft are modified by applying a lubricious coating, which changes the friction parameter between the outer shaft and the elastomeric seal. This parameter change reduces the frictional resistance, allowing the thin outer shaft to navigate tortuous vasculature more easily without experiencing excessive friction during advancement and device exposure
3Adaptability or versatility
If the elastomeric seal is made more resilient to accommodate different diameters, then the seal can accommodate both sheath and outer shaft, but friction between the seal and outer shaft still impedes motion
Solution Approach 1:
A lubricious coating is applied to the outer shaft surface to act as an intermediary layer between the outer shaft and the elastomeric seal. This coating reduces the coefficient of friction, allowing the outer shaft to slide more smoothly through the seal during advancement and device exposure, thereby reducing displacement while maintaining the necessary flexibility of the smaller-diameter outer shaft
Data Source
AI summary
A delivery device for an implantable medical device includes an inner shaft with a device-carrying region, an outer shaft surrounding the inner shaft, a sheath at a distal end of the outer shaft, and a sleeve. The outer shaft is movable relative to the inner shaft from an advanced position in which the sheath surrounds the device-carrying region to a retracted position in which the sheath exposes the device-carrying region. The sheath includes a proximal structure having a cylindrical portion between first and second transition zones. The sleeve surrounds the outer shaft and is movable relative to the outer shaft from an advanced position in which a distal end portion of the sleeve surrounds the cylindrical portion to a retracted position in which the distal end portion of the sleeve is spaced proximally from the cylindrical portion.