Flexible Intra-Vascular Stent Coil Flow Redirection
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Solution Overview
Problem
Conventional methods for treating aneurysms using wire stents often fail to effectively redirect blood flow away from the aneurysm, leading to increased pressure and risk of rupture.
Innovation Solution
A flexible intra-vascular stent with expanding coil portions is designed to receive blood flow on its upstream side and redirect it back toward the central lumen of the blood vessel, creating an eddy effect and pressure drop that draws blood from the aneurysm back into the lumen, thereby collapsing the aneurysm bubble.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire stent with raised strut portion is installed upstream of the aneurysm neck to redirect blood flow, then the intention is to create a pressure drop to draw blood out of the aneurysm, but the conventional design instead directs more blood flow into the aneurysm, increasing pressure and risk of rupture
Solution Approach 1:
The patent inverts the conventional stent design by positioning the raised strut portion downstream of the aneurysm neck rather than upstream. This reversal changes the flow dynamics so that the strut creates a pressure drop that draws blood out of the aneurysm, rather than directing blood into it. The inversion transforms the harmful effect into a beneficial one, achieving the intended therapeutic outcome.
Solution Approach 2:
The patent converts the potentially harmful effect of a raised strut (which can create turbulent flow and increase pressure) into a beneficial effect by strategically positioning it downstream. The strut still creates a pressure drop, but now this pressure drop is used to draw blood out of the aneurysm rather than pushing it in. The same mechanical principle produces opposite effects based on positioning.
2Strength
If the stent is made rigid to maintain structural integrity and prevent collapse, then the stent can withstand blood pressure, but the stent cannot be delivered through curved blood vessels
Solution Approach 1:
The stent is divided into multiple segments including a flexible proximal portion and a distal portion with raised struts. This segmentation allows different parts of the stent to have different properties - the proximal portion remains flexible for navigation through curved vessels, while the distal portion provides structural support and flow redirection. The modular design resolves the contradiction between flexibility and strength.
Solution Approach 2:
Different portions of the stent are given different mechanical properties locally. The proximal portion is made flexible to accommodate curved blood vessels during delivery, while the distal portion with raised struts is made more rigid to provide structural integrity and create the necessary pressure drop. This local differentiation allows the stent to satisfy both requirements simultaneously.
3Adaptability or versatility
If the stent is made flexible to navigate curved blood vessels during delivery, then the stent can be delivered to the target location, but the stent may collapse under blood pressure
Solution Approach 1:
The stent is segmented into a flexible proximal portion for navigation and a distal portion with raised struts for pressure resistance. This segmentation allows the stent to have flexible characteristics where needed during delivery, while maintaining structural strength where it is needed to withstand blood pressure and prevent collapse.
Solution Approach 2:
The stent exhibits dynamic properties where the proximal portion remains flexible during delivery and then expands to a more rigid state upon deployment. The raised struts in the distal portion provide immediate structural support. This dynamic behavior allows the stent to adapt its mechanical properties based on the operational phase - flexible for delivery, rigid for function.
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 effectively creates a pressure drop that draws blood out of the aneurysm and back into the blood vessel lumen, collapsing the aneurysm bubble and reducing pressure within it, thus addressing the limitations of conventional stent designs.
Implementation Method 1
creating an eddy effect proximate the downstream side/trailing edge of the respective coil portions
Implementation Method 2
creating a pressure drop (dP) which draws blood in the aneurysm bubble back into the lumen of the blood vessel
Data Source
AI summary
An intra-vascular aneurysm-treatment stent and a method for lowering pressure within an aneurysm bubble in a blood vessel. A stent coil is insertable into a blood vessel, the coil made of a material sufficiently flexible to move around curves, loops, and corners in the blood vessel. The stent coil is positioned in the blood vessel with selected stent coil portions proximate an opening into either a saccular aneurysm or a fusiform aneurysm. Blood in the lumen of the blood vessel flows past the leading edges and both over the outer surfaces, and under the inner surfaces. A portion of the blood inside the aneurysm becomes entrained with the blood flowing over the outer surfaces. At the trailing edges, the converging blood flows create eddies.