Biodegradable Implantable Filter Strut Modulation
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Solution Overview
Problem
Conventional vena cava filters face challenges in maintaining optimal radial force over time, with high initial force for secure implantation potentially becoming undesirable after tissue encapsulation, and existing designs may cause trauma or ingrowth due to step-changes in force distribution.
Innovation Solution
The development of an implantable medical device with struts that have a biodegradable reinforcement element, allowing the flexural modulus to vary continuously along the operative length, reducing radial force over time and providing a smooth, uniform radial outward force, minimizing stress points and trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter struts maintain high radial force continuously, then secure implantation is achieved, but tissue trauma and ingrowth increase over time
Solution Approach 1:
The filter strut incorporates a biodegradable reinforcement element that dynamically changes its mechanical properties over time. The reinforcement element degrades from an initial state providing high radial force for secure implantation to a final state with reduced radial force after tissue encapsulation, thereby adapting the force profile to match the changing physiological conditions and avoiding continuous high-force tissue trauma
Solution Approach 2:
The flexural modulus of the filter strut is changed over time through the biodegradation of the reinforcement element. The reinforcement element has a higher flexural modulus than the base strut material, and as it degrades, the overall flexural modulus decreases, resulting in a transition from high to low radial force output. This parameter change allows the strut to provide high initial fixation force while automatically reducing force after tissue encapsulation to prevent trauma
2Ease of manufacture
If uniform radial force is applied along the strut, then predictable deployment is achieved, but step-changes in force distribution cause trauma
Solution Approach 1:
The reinforcement element is designed with spatially varying properties along the length of the strut, creating local variations in flexural modulus. This allows different segments of the strut to provide different levels of radial force, with the reinforcement distributed non-uniformly to smooth out force transitions and eliminate step-changes that would otherwise cause localized trauma to the vessel wall
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 ensures a high initial radial force for secure implantation, followed by a reduction in force as the reinforcement degrades, reducing the risk of trauma and ingrowth, while allowing for predictable deployment across different vessel sizes.
Implementation Method 1
the reinforcement element is biodegradable thereby changing the flexural modulus of the strut from the second flexural modulus to the first flexural modulus as the reinforcement element biodegrades
Data Source
Figure 1A~1B
Figure 2~4
Figure 5A~13
AI summary
In an embodiment, an implantable medical device such as a filter includes a plurality of struts 22 arranged in a generally conical form with each strut 22 having a first end, a second end, and an operative length between the first and second ends. Each strut 22 is able to flex along its operative length 32 and includes a strut skeleton (34) having a first flexural modulus and a reinforcement element (36) extending along the operative length 32 and attached to the strut skeleton. The reinforcement element (36) and the strut skeleton (34) together have a second flexural modulus greater than the first flexural modulus. At least one of the reinforcement element (36) and the strut skeleton (34) varies in at least one of amount and composition continuously along the operative length 32 such that the second flexural modulus varies in a continuous manner along the operative length 32. The reinforcement element is biodegradable thereby changing the flexural modulus of the strut from the second flexural modulus to the first flexural modulus as the reinforcement element biodegrades.