Spiral Flow Inducing Stent for AVF Neointimal Hyperplasia
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Solution Overview
Problem
Arteriovenous fistulas (AVFs) used for hemodialysis often experience neointimal hyperplasia due to turbulent blood flow, leading to stenosis and potential failure, as the venous tissue responds abnormally to increased flow rates and pressure drops, which existing technologies have not effectively addressed.
Innovation Solution
A spiral flow inducing stent with helically shaped flow diverters, integrated with proximal and distal stent regions, is designed to promote laminar, spiral blood flow by cutting and bending sheet metal from a cannula to create a helical flow surface, which is then implanted near the AVF to potentially prevent or slow neointimal hyperplasia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an arteriovenous fistula is created to achieve high blood flow rates for hemodialysis, then the blood flow volume increases, but turbulent flow is generated causing neointimalhyperplasia and stenosis
Solution Approach 1:
The patent applies curvature by forming the stent into a spiral configuration with helical struts that follow a curved path along the longitudinal axis. This spiral geometry is designed to induce rotational flow patterns in the blood, transforming the straight cylindrical stent into a structure that generates beneficial flow dynamics to reduce turbulence and prevent neointimalhyperplasia while maintaining high flow rates
2Strength
If traditional straight stents are used to support the fistula, then structural support is provided, but turbulent flow patterns persist causing continued tissue proliferation
Solution Approach 1:
The patent transforms the traditional straight cylindrical stent into a spiral configuration where the struts follow a helical path. This curvature modification maintains the structural support function while fundamentally changing the flow dynamics from turbulent to rotational laminar flow, thereby eliminating the harmful turbulent flow patterns that cause tissue proliferation
Solution Approach 2:
The patent changes the geometric parameters of the stent from a straight configuration to a spiral configuration with specific helical angles and pitch. This parameter change transforms the flow regime from turbulent to rotational laminar flow while maintaining adequate structural support, thereby resolving the contradiction between structural integrity and flow pattern
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 stent induces spiral blood flow, reducing the progression of neointimal hyperplasia and maintaining healthy vascular function by mimicking native arterial blood flow patterns, thus extending the lifespan and effectiveness of AVFs.
Implementation Method 1
the native state of arterial blood flow may exhibit circumferentially oriented velocity components such that the blood flow is helical or spiral in nature
Implementation Method 2
The abnormal flow through an AVF appears to be generally turbulent rather than laminar
Data Source
AI summary
A cannula cut spiral flow inducing stent includes a plurality of spiral inducing flow diverters that each include a piece of sheet metal with a helically shaped flow surface. A proximal stent region, which includes a plurality of first struts, is joined to a proximal end of each of the spiral inducing flow diverters. A distal stent region, which includes a plurality of second struts, is joined to a distal end of each of the spiral inducing flow diverters. All of the first struts and all of the second struts share a cannula thickness, but the shaped pieces of sheet metal may have a lesser thickness.