Prosthesis Delivery Axial Spacing Mechanism
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Solution Overview
Problem
Existing deployment systems for stent grafts face challenges in accurate placement due to axial compression and movement during loading and deployment, leading to potential misplacement and unfavorable clinical consequences such as branch vessel occlusion and restenosis, caused by frictional interference and low columnar strength of the prosthetic implant.
Innovation Solution
A deployment system with an axial spacing mechanism that includes stent contact points to maintain the axial distance between stents, preventing axial compression and movement, using a flexible longitudinal member or tubular body secured to the introducer to retain the stent graft in a radially compressed configuration and ensure accurate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the prosthetic implant is loaded onto the inner cannula along the prosthesis retaining region, then the implant can be delivered to the lesion site, but axial compression and movement occur due to frictional interference between the outer sheath and the implant
Solution Approach 1:
A low-friction coating layer is applied to the outer sheath surface that contacts the prosthetic implant. This coating acts as an intermediary between the outer sheath and implant, reducing frictional interference and preventing axial compression and bunching during delivery and deployment while maintaining reliable placement accuracy
Solution Approach 2:
The surface properties of the outer sheath are modified by applying a low-friction coating, changing the friction parameter at the interface between the sheath and implant. This parameter change reduces the frictional force that causes axial compression, allowing smooth deployment without implant deformation
2Ease of operation
If the outer sheath is retracted relative to the inner cannula to allow implant expansion, then deployment occurs, but relative movement of the outer sheath causes axial compression and movement of the prosthetic implant
Solution Approach 1:
The low-friction coating on the outer sheath serves as a mediator during the retraction and deployment process, enabling smooth relative movement between the outer sheath and inner cannula assembly while preventing the outer sheath from causing axial compression that would compromise implant positioning precision
3Strength
If the prosthetic implant has low columnar strength, then the implant can be expanded against the surface of the outer sheath, but frictional interference exceeds the columnar strength causing deformation in the longitudinal direction
Solution Approach 1:
The low-friction coating on the outer sheath acts as a protective intermediary during the expansion phase, reducing the frictional forces that would otherwise exceed the implant's columnar strength and cause longitudinal deformation or buckling, thereby preserving structural integrity
Solution Approach 2:
By changing the friction parameter through coating application, the resistance to longitudinal compression is reduced below the implant's columnar strength threshold, preventing Euler buckling and maintaining structural integrity during deployment
4Ease of manufacture
If axial compression occurs during loading, then the implant can be loaded into the catheter, but the implant length is foreshortened leading to inaccurate placement relative to the lesion site
Solution Approach 1:
The low-friction coating on the outer sheath prevents excessive frictional forces during the loading process, eliminating axial compression that would foreshorten the implant and compromise length measurement accuracy, while still allowing smooth loading into the catheter
Data Source
AI summary
A deployment system is configured to deploy a prosthesis into an internal lumen of a patient. The system can include an introducer with the loaded prosthesis. A spacing mechanism can be disposed axially along the introducer. When the prosthesis is mounted onto the introducer in a radially compressed configuration, an end of a first stent and a second stent can engage a contact point of the spacing mechanism to maintain the axial distance between the first and second stents and prevent axial compression of the prosthesis during loading and deployment. The spacing mechanism can reside within the prosthesis and be disposed outwardly away from the introducer to contact the interior surface of the prosthesis. The spacing mechanism can include a flexible longitudinal member, such as a wire or strip, or a tubular body.