Segmented Sheathing for Implant Release and Navigation
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Solution Overview
Problem
Current devices for introducing implants into blood vessels face challenges in flexibility during navigation through narrow vessels and reliable release at the desired location, particularly in the cerebral region, where existing stents may not adequately adapt to vessel diameters and can cause unwanted pressure or dislodgment.
Innovation Solution
A device comprising an implant, a pusher wire, and a tube-like sheathing that allows the implant to deform within a microcatheter, expand at the placement site, and attach to a retaining element with varying outer diameters to ensure flexibility and secure release, featuring a distal section for high stiffness, a middle section for flexibility, and a proximal section for resistance to elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a uniform tube-like sheathing is used, then the structure is simple, but the device cannot provide both flexibility for navigation and resistance to elongation for reliable release
Solution Approach 1:
The tube-like sheathing is divided into multiple sections with different outer diameters: a distal section with larger outer diameter for stiffness and retention, a middle section with smaller outer diameter for flexibility during navigation, and a proximal section with larger outer diameter for resistance to elongation during release. This segmentation allows each section to perform its specific function optimally.
Solution Approach 2:
Different sections of the tube-like sheathing are designed with different local properties (varying outer diameters) to satisfy different functional requirements at different locations. The distal section provides retention stability, the middle section provides navigation flexibility, and the proximal section provides release reliability.
2Reliability
If a stent with wide-meshed wall is used to bar the aneurysm opening, then occlusion coils are prevented from being flushed out, but blood flow into the aneurysm is not prevented and access for aftertreatment is obstructed
Solution Approach 1:
The implant is designed to dynamically adapt its shape and density. It starts in a compressed state for delivery, then expands to its final shape at the placement site, increasing its braiding density to provide effective coil retention while maintaining appropriate blood flow characteristics and access.
Solution Approach 2:
The implant's physical parameters (diameter, braiding density, shape) change from the delivery state to the deployed state. This parameter transformation allows the same structure to serve multiple functions: delivery through narrow access, effective coil retention, and maintained aftertreatment access.
3Strength
If a stent is expanded hydraulically by balloon at the placement site, then the stent is attached to the vessel wall, but the balloon serves as transportation element which is not suitable for cerebral region implants
Solution Approach 1:
The implant is pre-formed in its final shape and size before delivery. It is manufactured as an elongated braided structure that automatically assumes its functional configuration upon deployment, eliminating the need for post-deployment balloon expansion and avoiding the use of balloons in cerebral procedures.
Solution Approach 2:
The mechanical balloon expansion system is replaced with a self-expanding implant mechanism. The implant uses its inherent elastic recovery to expand to its final shape without requiring external balloon assistance, making it suitable for cerebral applications where balloons are contraindicated.
4Ease of operation
If the tube-like sheathing is retracted to release the implant, then the implant can be deployed, but the tube may expand in longitudinal direction causing inaccurate translation and failure to release connecting element
Solution Approach 1:
The tube-like sheathing is segmented into sections with different outer diameters that provide different mechanical properties. The proximal and distal sections with larger diameters resist elongation during retraction, while the middle section with smaller diameter provides flexibility. This segmentation ensures accurate translation of retraction force to the implant release point.
Solution Approach 2:
Different sections of the tube-like sheathing have different local stiffness characteristics. The sections with larger outer diameters provide the necessary resistance to longitudinal expansion, ensuring that retraction at the proximal end accurately translates to the distal end where the implant is released.
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
Enables the implant to be guided through narrow blood vessels with high flexibility and ensures predictable, problem-free release, reducing the risk of dislodgment and improving adaptation to vessel diameters, thereby enhancing the safety and effectiveness of implant placement.
Implementation Method 1
the implant being capable of being deformed inside a microcatheter in a manner that allows it to assume a shape of reduced diameter and, after omission of such external constraint exerted by the microcatheter, expand at the placement site and adapt to the blood vessel diameter
Data Source
AI summary
The invention relates to a device for the introduction of an implant (1) into blood vessels of the human body, said device comprising an implant (1), a pusher or insertion wire (14), and a tube-like sheathing (13), wherein the implant (1) is capable of being deformed inside a microcatheter in a manner that allows it to assume a shape of reduced diameter and, after omission of such external constraint exerted by the microcatheter, expand at the placement site and adapt to the blood vessel diameter, and wherein the implant (1) being provided at the proximal end with connection elements (6) attaching it to a retaining element (15) by means of which the implant (1) is coupled to the pusher wire (14), and wherein the retaining element (15) is provided with peripheral cutouts (16) into which the connecting elements (6) are fitted, with the tube-like sheathing (13) being drawn in a form-closed manner over the retaining element (15) with fitted connection elements (6) such that the connection elements (6) are secured within the cutouts (16) of the retaining element (15) and the implant (1) being released by the retraction of the tube-like sheathing (13) in proximal direction, with the outer diameter of the tube-like sheathing (13) varying between the proximal and the distal end. In this manner, high pliability is achieved in some sections of sheathing (13) which is conducive to maneuvering through narrow blood vessels, and, moreover, sufficient tensile strength is available for the purpose of releasing implant (1).