Expandable AV Shunt Flow Restrictor Bands for Vein Stenosis
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Solution Overview
Problem
Current AV shunts for hemodialysis suffer from low patency rates due to vein stenosis and blood stealing from extremities, leading to ischemia and continuous cardiac output loss, necessitating frequent invasive procedures.
Innovation Solution
A mechanically adjustable flow restrictor band within the AV shunt that can be expanded, fractured, or made elastic to control the inner diameter, minimizing stenosis and maintaining cardiac output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flow restrictor band is added to the AV shunt, then vein stenosis is reduced and shunt life is extended, but device complexity increases
Solution Approach 1:
The flow restrictor band is nested within the AV shunt structure, with the band positioned inside the shunt lumen. This nested configuration allows the restrictor to be integrated into the existing shunt without requiring separate external components, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The flow restrictor band is constructed as a flexible, thin-walled structure that can be expanded and contracted. This flexible design allows the band to conform to the shunt geometry and provide effective flow restriction through its narrowed inner diameter, addressing the patency issue without adding substantial structural complexity.
2Loss of energy
If the restrictor band inner diameter is reduced to create flow restriction, then blood stealing is decreased, but pressure loss increases
Solution Approach 1:
The flow restrictor band creates a localized restriction at a specific position within the AV shunt, rather than uniformly reducing flow throughout the entire shunt length. This localized approach allows blood stealing to be decreased at the restriction point while maintaining adequate flow and pressure in other sections of the shunt, thereby reducing cardiac output loss without excessive pressure loss.
3Duration of action of stationary object
If a mechanical band is used to restrict flow, then shunt life is extended, but ease of operation decreases
Solution Approach 1:
The flow restrictor band is designed with dynamic characteristics, allowing it to be expanded and contracted to adjust the inner diameter. This dynamic design enables the restrictor to be modified if hemodynamics or patient clinical condition changes, maintaining ease of operation while extending shunt life through adjustable flow restriction.
4Adaptability or versatility
If the restrictor band is made expandable, then adaptability improves, but device complexity increases
Solution Approach 1:
The restrictor band employs a flexible, thin-walled structure that inherently provides expandability without requiring complex mechanical components. This flexible design allows the band to be expanded and contracted for flow restriction adjustment, improving adaptability while keeping the device structure relatively simple and avoiding excessive complexity.
Data Source
AI summary
A shunt comprising a flexible tube having a first, and a second end, and a central opening, having a first diameter that extends from the first end to the second end. The shunt also includes one or more restrictor bands having a second diameter around the flexible tube. The one or more restrictor bands are located between the first end and the second end of the flexible tube and the second diameter is less than the first diameter such that the restrictor band forms a restriction. The restrictor band is expandable between a first position and a second position. The restrictor band may have fracturable sections configured to fracture in responds to pressure thereby increasing a diameter of the one or more restrictor bands to a diameter greater than the second diameter. The one or more restrictor bands may comprise restrictor bands of at least two different inner diameters.