Bioabsorbable Endovascular Stent With Superelastic Nitinol Connectors
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Solution Overview
Problem
Current endovascular devices face challenges such as limited biodegradability, thrombogenicity, and the need for invasive surgeries, particularly in pediatric patients, due to the use of non-degradable materials that can cause long-term complications and require multiple surgeries for growth and durability issues.
Innovation Solution
Development of superelastic, bioabsorbable endovascular devices constructed from biodegradable metals like magnesium and iron, combined with superelastic nitinol connectors and biodegradable polymers like polyurethane urea, which can be elastically deformed for catheter-based delivery and deployable in the body, reducing the risk of foreign body reactions and promoting tissue integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-degradable materials (metals and polymers) are used in endovascular devices, then mechanical strength and durability are improved, but biodegradability worsens and long-term foreign body complications increase
Solution Approach 1:
The device is divided into multiple segments including a balloon catheter, stent framework, and valve leaflets that can be separately controlled and deployed. This segmentation allows the device to be delivered in a compressed state and then expanded to provide mechanical support, achieving both deliverability and structural integrity
Solution Approach 2:
The invention uses composite materials combining biodegradable polymers (PLLA, PGA, PCL) with metallic components (nitinol). The biodegradable polymer provides initial structural support and gradually degrades over time, while the nitinol framework maintains mechanical strength. This composite approach resolves the contradiction between immediate mechanical strength and long-term biodegradability
2Duration of action of stationary object
If mechanical heart valves are used, then durability is improved (20-30 years), but thrombogenicity worsens requiring daily anticoagulant treatment
Solution Approach 1:
The invention changes the material parameters from traditional non-biodegradable mechanical valve materials to biodegradable polymers and tissues. The valve is designed to be temporarily supported by a stent framework that degrades over time, allowing the valve to transition from a mechanically supported structure to a tissue-based structure that is less thrombogenic and more compatible with blood flow
3Object-generated harmful factors
If bioprosthetic heart valves are used, then thrombogenicity is improved (no anticoagulant therapy needed), but durability worsens (10-15 years due to calcification and tissue failure)
Solution Approach 1:
The invention introduces a dynamic, multi-phase degradation process where the stent framework progressively degrades over time while the valve tissue remodels and strengthens. The device transitions from a fully supported artificial structure to a tissue-based valve, combining the initial durability of mechanical support with the long-term biocompatibility of tissue valves
Solution Approach 2:
The stent framework provides preliminary structural support and mechanical strength during the critical early healing phase, protecting the newly implanted valve tissue. This preliminary support allows the valve to mature and remodel without immediate mechanical failure, addressing the durability limitation of traditional bioprosthetic valves
4Strength
If traditional endovascular devices are used in pediatric patients, then initial structural support is provided, but adaptability worsens requiring multiple surgeries for growth
Solution Approach 1:
The stent framework is designed to provide excessive initial structural support that exceeds the minimum required, ensuring adequate mechanical strength during the critical early period. As the framework gradually degrades, it transfers load to the growing tissue, allowing the device to adapt to patient growth without requiring replacement
Solution Approach 2:
The invention changes the temporal parameters of structural support by using biodegradable materials with controlled degradation rates. The stent framework provides maximum support initially and progressively reduces support over time, matching the growth and strengthening of the patient's own tissue, thereby achieving growth adaptability
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 devices provide improved mechanical properties and biodegradability, minimizing long-term complications, allowing for less invasive procedures, and promoting tissue growth, with the potential to grow with children, reducing the need for multiple surgeries and minimizing foreign body reactions.
Implementation Method 1
biodegradable metals like magnesium and iron
Implementation Method 2
biodegradability, allowing for less invasive procedures
Implementation Method 3
superelastic nitinol connectors and biodegradable polymers like polyurethane urea, which can be elastically deformed for catheter-based delivery
Data Source
AI summary
The invention relates to endovascular medical implant devices and materials of composition for forming these devices to provide improved mechanical properties and biodegradability. The devices include a combination or integration of superelastic material, biodegradable metal and, thin film nitinol and/or biodegradable polymer. A structural frame is formed of individual elongated pieces composed of biodegradable metal. These pieces are joined together by connector pieces composed of superelastic material. At least a portion of the structural frame has deposited thereon the thin film nitinol and/or biodegradable polymer. The structural frame of the device is collapsible for insertion in a delivery tube and, recoverable for deployment and placement in a vascular location of a patient body.