Catheter Sheath Splitting via Dual Pull Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catheter delivery systems face challenges in removing thin-walled sheaths from the body without tearing or causing the endoprosthesis to move, especially when dealing with small endoprostheses in narrow blood vessels, due to high friction and the risk of sheath stretching or tearing during withdrawal.
Innovation Solution
A catheter delivery system with a dual pull element mechanism, where a first pull element splits the sheath along its length and a second pull element removes the sheath after splitting, reducing friction by keeping the sheath partially expanded during removal and using a hydrophilic coating to minimize friction with the vessel wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin-walled sheath is used to reduce the profile of the distal catheter end, then the ability to deliver small endoprostheses in narrow vessels is improved, but the risk of sheath tearing or stretching during removal increases
Solution Approach 1:
The sheath is divided into two separate sheath portions (first sheath portion and second sheath portion) that can be independently removed. This segmentation allows each portion to be managed separately, reducing the risk of tearing or stretching during removal while maintaining the thin-walled design for small endoprostheses delivery
Solution Approach 2:
The sheath is pre-cut with incisions or scored lines at specific locations before delivery. These preliminary cuts create controlled separation points that allow the sheath to split cleanly during removal, preventing uncontrolled tearing or stretching of the thin-walled structure
2Ease of operation
If the sheath is pulled from its proximal end for removal, then the removal process is simplified, but friction between the sheath and endoprosthesis may cause the endoprosthesis to move proximally
Solution Approach 1:
The sheath is divided into two portions that are removed separately. The first sheath portion is removed while the second sheath portion remains in place to continue supporting the endoprosthesis, preventing proximal movement during the removal process
Solution Approach 2:
The second sheath portion acts as an intermediary support structure that remains between the endoprosthesis and the pulling force during removal. This intermediary element prevents direct transmission of friction forces to the endoprosthesis, maintaining its axial position
3Manufacturing precision
If a thin-walled sheath is used to facilitate accurate placement of small endoprostheses, then delivery precision is improved, but the friction generated during removal may cause the sheath to tear
Solution Approach 1:
The thin-walled sheath is segmented into two portions with a predetermined separation point. This segmentation allows the sheath to be removed in sections, reducing the total friction force required for removal and preventing tearing of the thin walls while maintaining the thin-walled design for accurate placement
Solution Approach 2:
The sheath is pre-cut with incisions or scored lines that create controlled separation points. These preliminary actions weaken the sheath at specific locations, allowing it to split cleanly during removal without tearing the thin-walled structure, while maintaining the integrity needed for accurate delivery
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
This approach allows for the reliable and simplified removal of the sheath with reduced force requirements, minimizing the risk of sheath damage and endoprosthesis displacement, particularly beneficial for small endoprostheses in narrow vessels.
Implementation Method 1
expresses a preference for polyethylene-terephthalate as material for the body of the sheath because it tears easily after being notched
Implementation Method 2
using a hydrophilic coating to minimize friction with the vessel wall
Data Source
AI summary
A delivery system for a self-expanding device for placement in a bodily lumen, the system comprising a sheath that confines the device to a radially compact delivery disposition until the device is to be released into the lumen, the system having an elongate pull element to be pulled proximally from its proximal end, which pull element is arranged radially inside the sheath for pulling preferentially on a pull zone on the circumference of the distal end of the sheath, thereby to tear the sheath progressively along a tear line running the length of the sheath, starting at the distal end of the sheath, to release the device from the confining effect of the sheath, progressively, beginning at the distal end of the device and wherein the sheath is of polyethylene-terephthalate, cold drawn along its long axis, and in that the distal end of the sheath tapers inwardly to provide an inwardly tapered distal end of the system.