Stent-Graft Release Device Using Flexible Suture
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Solution Overview
Problem
Existing delivery and release devices for stent-grafts face challenges with difficult operation, inaccurate positioning, and high costs due to the use of rigid metal bars, which can cause permanent deformation of the stent-graft, leading to failure in releasing the stent-graft effectively.
Innovation Solution
A delivery and release device featuring a cone-shaped guiding head with a flexible tightening member, a central tube, and a positioning mechanism that uses a flexible tightening member to securely attach and release the stent-graft without causing deformation, ensuring accurate positioning and high success rate of release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotatable shaft is used to release the controlling suture, then the stent-graft can be released, but the torque cannot be effectively transmitted and the operation becomes difficult
Solution Approach 1:
The patent replaces the rotatable shaft mechanism with a pushrod that transmits linear pushing force directly to the controlling suture. This mechanical substitution eliminates the torque transmission problem inherent in rotational systems with large length-diameter ratios, providing more reliable and easier operation for releasing the stent-graft.
Solution Approach 2:
The patent extracts the rotatable shaft component from the system and replaces it with a simpler pushrod mechanism. By removing the problematic rotational element, the design achieves better torque transmission and easier operation without compromising the stent-graft release function.
2Ease of operation
If a rotatable shaft is used to release the stent-graft, then the controlling suture can be unwound, but the already positioned delivery device may shift position causing inaccuracy
Solution Approach 1:
The patent replaces the rotatable shaft with a pushrod that provides linear, controlled motion. This substitution prevents the position shifting problem that occurs during rotational unwinding, as the pushrod's linear movement can be precisely controlled without causing the delivery device to rotate or shift, thereby maintaining release position accuracy.
3Strength
If rigid metal bars are used to fasten the stent-graft, then the stent-graft can be securely attached, but the cost increases and permanent deformation may occur
Solution Approach 1:
The patent changes the material parameter from rigid metal to flexible controlling suture. This parameter change maintains the attachment strength needed to secure the stent-graft during delivery while reducing manufacturing cost and eliminating the risk of permanent deformation to the stent-graft structure.
Solution Approach 2:
The patent uses a flexible controlling suture instead of rigid metal bars to fasten the stent-graft. The flexible nature of the suture allows it to conform to the stent-graft without causing deformation, while still providing sufficient strength to secure it during the delivery process, and significantly reduces manufacturing cost.
4Strength
If rigid metal bars are used to pass through the projecting loops, then the stent-graft can be fastened, but permanent deformation of the stent-graft may occur
Solution Approach 1:
The patent changes the material parameter from rigid metal to flexible controlling suture. This parameter change maintains the attachment strength needed to secure the stent-graft while eliminating the harmful effect of permanent deformation, as the flexible suture can pass through the projecting loops without exerting excessive localized stress.
Solution Approach 2:
The patent uses a flexible controlling suture to pass through and fasten the projecting loops of the stent-graft. The flexibility of the suture allows it to navigate through the loops smoothly without causing permanent deformation to the stent-graft structure, while still providing sufficient attachment strength.
5Ease of operation
If the controlling suture is wound around the rotatable shaft, then the stent-graft can be released by rotation, but knotting or crossing may prevent the suture from stretching
Solution Approach 1:
The patent replaces the rotatable shaft winding mechanism with a linear pushrod system that pushes the controlling suture to stretch and release the stent-graft. This substitution eliminates the knotting and crossing problems inherent in rotational winding, ensuring reliable suture stretching and consistent stent-graft release.
Data Source
AI summary
A delivery and release device for stent-graft includes a guiding head and a central tube connected thereto, an outer tube sleeving on the outside of the central tube, a positioning tube sheathed between the central tube and the outer tube, a front fixator, a back fixator and a positioner successively sheathed between the positioning tube and the outer tube. The stent-graft is placed between the back fixator and the positioner. A metal bar is connected to the guiding head along its axial direction with a ring suture being connected to the front fixator. The ring suture sleeves onto the metal bar after passing through the stent-graft. During the release process, the metal bar moves forward in the axial direction to detach from the ring suture, thereby the stent-graft is released.