Pull-back Sheath Segmentation for Stent Delivery
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Solution Overview
Problem
Current delivery systems for self-expanding stents fail to reliably position stents in curved sections of blood vessels, such as the aortic arch, due to rigid pull-back sheaths that kink and jam, making precise placement and release difficult, risking vessel wall damage.
Innovation Solution
A pull-back sheath with a highly flexible front section made of textile material and a stiffer rear section made of polymer material, designed to transmit torsional and traction forces, allowing for easy adaptation to curved vessels and precise positioning without jamming, while a detachable conical tip and guide wire catheter facilitate safe insertion and withdrawal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid pull-back sheath is used to maintain stent compression during delivery, then the stent remains stable in compressed state, but the sheath kinks and jams in curved vessels making positioning difficult
Solution Approach 1:
The pull-back sheath is divided into two distinct sections: a first section made of flexible textile material that contacts the stent, and a second section made of stiffer polymer material for force transmission. This segmentation allows each section to perform its specialized function - the flexible section adapts to curved vessels without kinking while the stiffer section maintains structural integrity for transmitting torsional and traction forces during positioning and release.
Solution Approach 2:
Different material properties are applied to different sections of the pull-back sheath to optimize local functionality. The first section in contact with the stent uses flexible textile material for smooth interaction and vessel adaptation, while the second section uses stiffer polymer material for effective force transmission. This local differentiation resolves the contradiction between flexibility needed for curved vessels and rigidity needed for stable force transmission.
2Ease of operation
If a flexible pull-back sheath is used to adapt to curved vessels, then positioning in aortic arch is easier, but the sheath cannot transmit sufficient torsional and traction forces for precise stent placement
Solution Approach 1:
The pull-back sheath is divided into two distinct sections: a first section made of flexible textile material that contacts the stent, and a second section made of stiffer polymer material for force transmission. This segmentation allows each section to perform its specialized function - the flexible section adapts to curved vessels without kinking while the stiffer section maintains structural integrity for transmitting torsional and traction forces during positioning and release.
Solution Approach 2:
Different material properties are applied to different sections of the pull-back sheath to optimize local functionality. The first section in contact with the stent uses flexible textile material for smooth interaction and vessel adaptation, while the second section uses stiffer polymer material for effective force transmission. This local differentiation resolves the contradiction between flexibility needed for curved vessels and rigidity needed for stable force transmission.
3Device complexity
If a single-material pull-back sheath is used, then the structure is simple, but it cannot simultaneously provide flexibility for curved vessels and rigidity for force transmission
Solution Approach 1:
The pull-back sheath is divided into two distinct sections: a first section made of flexible textile material that contacts the stent, and a second section made of stiffer polymer material for force transmission. This segmentation allows each section to perform its specialized function - the flexible section adapts to curved vessels without kinking while the stiffer section maintains structural integrity for transmitting torsional and traction forces during positioning and release.
Solution Approach 2:
The pull-back sheath combines two different materials - flexible textile material and stiffer polymer material - into a composite structure. Each material contributes its advantageous properties to the overall system, enabling the sheath to simultaneously exhibit flexibility for navigating curved vessels and rigidity for transmitting positioning forces, thereby achieving dual functionality that a single material cannot provide.
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 reliable and precise positioning of stents in narrow, curved vessels like the aortic arch without damaging the vessel wall, reducing the force required for release and preventing stent jamming, ensuring safe and effective deployment.
Implementation Method 1
By virtue of the resiliency of the metal frame, the stent expands again into its original shape
Implementation Method 2
the stent is radially compressed such that its cross-sectional surface area greatly decreases
Implementation Method 3
By virtue of the resiliency of the metal frame, the stent expands again into its original shape and thus braces its circumferential surface
Data Source
AI summary
A delivery system is equipped with a self expanding stent for implantation into a blood vessel, in particular in the region of the aortic arch. The stent has a hollow cylindrical body which is radially compressed for implantation. A pull-back sheath which surrounds the stent and which radially compresses it is also provided for positioning and releasing the stent in the blood vessel. The pull-back sheath has a highly flexible front section which surrounds the stent and which maintains said stent in its compressed state, and has further a more rigid rear section which is connected to the front section and which is designed to transmit torsional and traction forces to the front section.