Self-Adjusting Venous Graft with Pressure-Sensitive Stenosis
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Solution Overview
Problem
Current vascular grafts used for hemodialysis, such as AVFs and AVGs, have poor patency rates due to unnatural flow dynamics, leading to frequent graft failure and increased healthcare costs, as the body's physiological defenses attempt to return the system to normal by healing the access points, causing clotting and intraluminal scarring.
Innovation Solution
A self-adjusting venous equalizing graft (SAVE graft) with a self-regulating stenosis that mimics natural physiology, featuring an endothelial lining and drug-eluting materials to reduce clotting and cellular growth, and a collapsible and expandable conduit design that adjusts blood flow based on pressure changes, maintaining optimal venous outflow pressures and flow rates without operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional AVFs or AVGs are used to provide hemodialysis access, then large volume blood access is achieved, but the body's physiological defenses cause clotting and intraluminal scarring leading to poor patency rates
Solution Approach 1:
The graft incorporates pressure-sensitive elements that automatically adjust the stenosis opening based on blood flow pressure without external intervention. When pressure increases, the opening constricts; when pressure decreases, the opening widens, allowing the system to self-regulate and prevent clotting
Solution Approach 2:
The graft dynamically changes the stenosis opening parameter in response to pressure changes. The pressure-sensitive material alters its physical state based on pressure, transforming the fixed geometry into a variable geometry that adapts to physiological conditions
2Stress or pressure
If a stenosis is provided in the graft to regulate flow, then venous outflow pressure can be controlled, but the stenosis may become obstructed by clotting and cellular growth
Solution Approach 1:
The stenosis opening is made dynamic through the use of pressure-sensitive material that automatically adjusts the opening size based on blood flow pressure. This dynamic adjustment prevents stasis and reduces the risk of clotting and cellular growth obstruction
Solution Approach 2:
The pressure-sensitive element provides automatic feedback control where increased pressure causes constriction and decreased pressure causes dilation, creating a self-regulating system that maintains optimal flow conditions
3Productivity
If high arterial blood pressure is shunted directly to the vein to provide large volume blood flow, then dialysis access is improved, but venous pressure becomes excessively high causing complications
Solution Approach 1:
The graft transforms the high-pressure arterial flow into controlled venous outflow by using pressure-sensitive material that responds to pressure changes, automatically adjusting the stenosis opening to regulate venous pressure within safe limits
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
The SAVE graft improves patency rates by reducing clotting and cellular growth, normalizing venous outflow pressures, and preventing steal syndrome, thereby extending the life of the graft and reducing healthcare burdens.
Implementation Method 1
The stenosis provided by the graft may be formed from a pressure-sensitive material configured to constrict or dilate the stenosis opening in response to pressure changes
Implementation Method 2
The non-thrombogenic property of the endothelium may be used to prevent blood from clotting
Implementation Method 3
The drug eluting material may stop cellular proliferation
Data Source
AI summary
An improved vascular graft having increased patency is disclosed herein. The graft may comprise a central or other stenosis. In addition, in some embodiments, the graft may comprise an internal reservoir and a collapsible portion configured to self-adjust the stenosis based on blood flow pressure. The graft may comprise an endothelial lining, one or more drug eluting materials, or both to increase patency by respectively reducing clots and preventing unwanted cellular or fibrin growth. The endothelial lining may be formed from one or more endothelial cells artificially grown or harvested from a patient's vascular system.