Reversible Flow Restrictor for AV Fistula Maturation
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Solution Overview
Problem
Existing methods for creating arteriovenous (AV) fistulas often result in delayed maturation due to split blood flow among multiple outflow veins, and permanently ligating these veins renders them unusable for future access.
Innovation Solution
A reversible flow restrictor system is introduced, comprising an expandable structure or basket with anchoring members, which can be placed in competing outflow veins to reduce blood flow and direct it into the intended vein for dialysis, while preserving the patency of these veins for potential future use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If permanent ligation of collateral veins is performed to increase flow to the primary vein, then fistula maturation is accelerated, but the collateral veins are permanently lost for future use
Solution Approach 1:
The flow restrictor device employs a dynamic structure with expandable elements that can be adjusted between different states. The device includes an expandable cage-like structure with radially extendable elements that can be expanded to restrict flow or collapsed to allow normal flow, enabling reversible control of blood flow to the collateral vein without permanent ligation
Solution Approach 2:
The device changes the flow parameters by adjusting the degree of expansion of the restrictor elements. By varying the radial position of the expandable elements, the device can modulate the resistance to blood flow in the collateral vein, allowing control of flow distribution between primary and collateral veins while preserving future access options
2Productivity
If flow restrictor is deployed to reduce blood flow in collateral veins, then more blood flows to the primary vein for dialysis, but the device complexity increases
Solution Approach 1:
The flow restrictor device is divided into multiple independent radially extendable elements or struts that can be individually controlled. Each element can be expanded or collapsed independently, allowing precise control of flow restriction while maintaining structural integrity. This segmentation enables simplified control mechanisms and easier deployment
Solution Approach 2:
The expandable flow restrictor elements are designed with a nested configuration where smaller structural components are contained within larger ones during delivery, and then expanded to the functional configuration at the target site. This nesting approach simplifies delivery through catheters while enabling complex three-dimensional structures at the deployment site
Data Source
AI summary
A method of producing an arteriovenous (AV) fistula includes producing an anastomosis between a primary blood vessel (e.g., a vein) and a secondary blood vessel (e.g., an artery). A collateral (or competing) blood vessel in fluid communication with one of the primary blood vessel or the secondary blood vessel is identified. A reversible flow restrictor is then applied to the collateral blood vessel to reduce a blood flow rate through the collateral blood vessel. In some embodiments, the anastomosis can be produced percutaneously. In some embodiments, the reversible flow restriction (or a portion thereof) can be removed from the collateral blood vessel. In other embodiments, the reversible flow restriction (or a portion thereof) can be adjusted to allow increased blood flow therethrough while within the collateral blood vessel.