Reduced Profile AAA Endoprosthesis Nested Stent Design
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Solution Overview
Problem
Current endoprostheses for treating abdominal and thoracic aortic aneurysms face challenges such as high mortality and morbidity rates due to invasive surgical procedures, difficulty in positioning and anchoring, risk of endoleaks, and interference with normal blood flow, especially in complex vessel geometries and larger vessels like the thoracic aorta.
Innovation Solution
A reduced profile endoprosthesis with a self-expanding stent made from shape memory alloy, such as NiTi, and biocompatible graft material, featuring a cranial section with a bifurcated design that allows for nesting and enhanced expansion ratio, providing a durable and re-configurable fluid tight seal, and percutaneous delivery via catheters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surgical bypass with graft placement is used, then aneurysm repair is achieved, but mortality rate increases and recovery period extends
Solution Approach 1:
The patent replaces open surgical mechanical procedures with endovascular catheter-based delivery. The endoprosthesis is delivered through a catheter inserted via the femoral artery, eliminating the need for large abdominal incisions and open surgical exposure, thereby reducing recovery time while maintaining repair effectiveness
Solution Approach 2:
The patent introduces a catheter as an intermediary delivery mechanism. The endoprosthesis is transported through the catheter from the femoral artery to the aneurysm site, serving as a mediator that enables minimally invasive placement without requiring direct surgical access to the abdominal cavity
2Object-affected harmful factors
If endovascular stent-graft is used, then surgical morbidity is reduced, but device positioning and anchoring becomes more difficult
Solution Approach 1:
The endoprosthesis is divided into multiple expandable stent sections that can be independently positioned and deployed. The device includes a proximal section, distal section, and intermediate section that can be selectively expanded to achieve precise positioning and anchoring in complex vessel geometries
Solution Approach 2:
The stent sections are designed to be dynamically expandable from a compressed delivery state to a fully expanded anchoring state. The self-expanding mechanism allows the device to transition from a delivery configuration suitable for catheter passage to a functional configuration that provides secure anchoring in the aorta
3Reliability
If standard endoprosthesis is used, then aneurysm exclusion is achieved, but endoleaks occur and blood flow is interfered with
Solution Approach 1:
The endoprosthesis features locally adapted sealing structures at critical locations. The proximal and distal sections include specialized sealing elements designed to conform to the specific anatomy of the aortic neck and bifurcation, creating fluid-tight seals that prevent endoleaks while maintaining appropriate blood flow through the graft
Solution Approach 2:
The graft material is constructed as a flexible tubular structure that can conform to the vascular anatomy. The flexible nature allows the graft to adapt to the aortic geometry and provide effective sealing at the proximal and distal ends while maintaining patency and appropriate blood flow characteristics
4Ease of operation
If percutaneous delivery is used, then invasive surgery is avoided, but device profile must be reduced for catheter delivery
Solution Approach 1:
The endoprosthesis is designed with a nested configuration for delivery. The stent sections and graft material can be compressed and nested within each other to create a compact profile that fits within the constraints of percutaneous catheter delivery, while still expanding to full size at the deployment site
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 solution enables safer, less invasive treatment with reduced surgical risks, improved anchoring and sealing in complex vessels, and efficient blood flow management, facilitating acute and long-term fluid tight seals, and reducing the need for open surgical intervention.
Implementation Method 1
A reduced profile endoprosthesis with a self-expanding stent made from shape memory alloy, such as NiTi
Data Source
AI summary
An abdominal aortic aneurysm endoprosthesis having a reduced profile for percutaneous delivery of the endoprosthesis. The endoprosthesis provides a cranial section supported by a stent, and a bifurcated caudal section having at least two legs each of which are supported by individual stents. The individual stents of each leg of the caudal section are staggered so as not to line up with one another. Altering the lengths of the legs permits nesting of the endoprosthesis. Optimizing the expansion ratio and radial strength of the endoprosthesis is achieved by altering the dimensions of the starting material from which the stent segments are fabricated, by altering the final austentite temperature of the starting materials, or by changing the structural configuration of the stent segments. A graft material is attached to at least a portion of the cranial section and to all of the caudal section of the endoprosthesis.