Lyophilized Tissue Valve for Minimally Invasive Delivery
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Solution Overview
Problem
Tissue valves made from biologic origin face challenges such as immune response, sterility, storage stability, durability, and minimally invasive surgical requirements, particularly for collapsible valves that need to be compressed and robust enough for transvascular introduction and expansion.
Innovation Solution
The method involves lyophilization (freeze-drying) of tissue valves or their components before or after assembly, reducing moisture content and allowing for smaller delivery devices, eliminating the need for storage in hydrating solutions, and enabling pre-loading onto smaller diameter delivery devices with sterile packaging for reconstitution in situ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tissue valves are compressed into a small profile for transvascular introduction, then ease of operation is improved, but tissue durability and structural integrity deteriorate
Solution Approach 1:
The patent applies parameter changes by transitioning the tissue from a hydrated state to a lyophilized (freeze-dried) state. This fundamental parameter change in moisture content transforms the tissue mechanical properties, enabling it to be compressed to a small profile for transvascular introduction while maintaining structural integrity during the compressed state. The lyophilized tissue can withstand the stresses of mounting onto stents and being compressed into delivery catheters.
Solution Approach 2:
The patent implements preliminary action by performing lyophilization of the tissue valve components before assembly and implantation. The tissue is freeze-dried in advance to achieve the desired mechanical properties and low moisture content (about 10% or less) that enable subsequent compression and transvascular delivery without compromising tissue durability during the compression process.
2Reliability
If tissue valves are made robust enough to withstand mounting stresses and expansion, then reliability is improved, but device complexity and difficulty of delivery increase
Solution Approach 1:
The patent resolves this contradiction through parameter changes in the tissue moisture content. By reducing moisture to about 10% or less through lyophilization, the tissue achieves enhanced mechanical robustness and durability to withstand mounting stresses and prolonged use, while simultaneously becoming sufficiently compressible to be delivered through transvascular routes. This parameter transformation enables both reliability and simplified delivery.
3Duration of action of stationary object
If tissue valves are stored in hydrating solutions to maintain tissue viability, then tissue durability is improved, but storage cost and chemical waste increase
Solution Approach 1:
The patent applies the extraction principle by removing the need for hydrating storage solutions through lyophilization. The tissue is freeze-dried to such low moisture content that it can be stored in a stable, dry state without chemical preservatives or hydrating solutions. This eliminates the requirement for special storage conditions and removes the associated chemical waste, while maintaining tissue viability until implantation when the tissue rehydrates in situ.
Solution Approach 2:
The patent implements a disposable-like storage approach where the tissue valve is provided in a stable, dry, lyophilized state that requires no expensive storage infrastructure or chemical solutions. The valve can be stored indefinitely in a simple dry environment and then activated by rehydration during implantation, eliminating ongoing storage costs and chemical waste.
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
Lyophilization enhances the durability and convenience of tissue valves, reduces storage and transport costs, minimizes chemical waste, and allows for precise crimping and loading, facilitating minimally invasive procedures while ensuring the valves are introduced substantially free of dehydrating chemicals.
Implementation Method 1
lyophilization (freeze-drying) of tissue valves or their components before or after assembly, reducing moisture content
Implementation Method 2
lyophilization of the tissue can occur before or after construction of a valve assembly... the entire resulting tissue valve is lyophilized
Data Source
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AI summary
A method of making a tissue valve (10). The method includes the step of attaching a valve assembly (30) comprised of at least one leaflet (32) to an interior surface of a stent (20) configure to fit within at least one blood vessel. The method also includes the step of lyophilizing the valve assembly (30).