Arteriovenous Graft Valve With Zero-Volume Closure Against Thrombosis
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Solution Overview
Problem
Existing arteriovenous grafts suffer from complications such as arterial steal and graft thrombosis, which can lead to reduced blood flow and clotting, necessitating post-dialysis flushing to prevent clotting.
Innovation Solution
An arteriovenous graft system with a valve device that can be switched between open and closed states, allowing blood flow during dialysis and blocking flow when not in use, thereby minimizing internal volume to zero in the closed state to prevent clotting without the need for flushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vein is used as a graft for hemodialysis, then the patient can be connected to the dialysis machine, but the vein may not have sufficient blood flow or adequate size
Solution Approach 1:
The graft system is divided into multiple segments: a biocompatible tube segment (Dacron or ePTFE) and a vein segment, connected via an anastomosis. This segmentation allows the system to overcome the limitations of using a small vein alone by combining it with a larger synthetic tube that provides sufficient diameter for dialysis access.
Solution Approach 2:
The biocompatible tube acts as an intermediary component between the artery and the vein. It is joined to the vein to create an arteriovenous graft, serving as a mediator that provides the necessary blood flow capacity while the vein provides biological compatibility and anchoring.
2Reliability
If a vein is used as a graft, then the patient can access dialysis, but blood clots may form in the vein
Solution Approach 1:
The biocompatible tube serves as an intermediary that reduces direct arterial blood flow into the vein, which decreases the risk of blood clot formation. The tube modifies the hemodynamic conditions by providing a transition zone that reduces turbulence and stasis in the vein portion.
Solution Approach 2:
The system changes the flow parameters by introducing a tube with different diameter and surface properties than the native vein. This alters the blood flow velocity and pressure distribution, reducing conditions that promote clot formation while maintaining adequate flow for dialysis.
3Stability of the object's composition
If an arteriovenous valve device is implanted in the vein, then blood flow direction is controlled, but the device adds complexity to the graft system
Solution Approach 1:
The arteriovenous valve device is merged with the vein graft to form an integrated arteriovenous valve graft. This combination ensures proper blood flow direction while maintaining a relatively simple overall structure that can be implanted as a single unit.
4Reliability
If surgical anastomosis is performed to join the vein to the artery, then blood flow is established, but the surgical procedure is complex and time-consuming
Solution Approach 1:
The vein is harvested and prepared outside the body before implantation. The anastomosis is performed on the harvested vein segment in a controlled setting, and then the prepared graft is implanted. This preliminary preparation simplifies the actual surgical implantation procedure.
Data Source
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AI summary
The invention provides a subcutaneous arteriovenous graft system, comprising an arteriovenous graft having an arterial end, a venous end opposite to the arterial end and an internal volume between the arterial end and the venous end, and a valve device that can be arranged in an open state, in which fluid flow through the graft is possible and a closed state in which the fluid flow through the arteriovenous graft is blocked.The valve device is constructed to decrease, in the closed state of the valve device, the internal volume of the complete graft to substantially zero.