Electrospun Polymer Cuff for TAVI Valve Leaflets
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Solution Overview
Problem
Current methods for producing prosthetic aortic heart valves for transcatheter implantation require separate formation and connection of valve leaflets and stent sealing, which is time-consuming, prone to human error, and costly, and existing materials face challenges with long-term biostability and thrombosis.
Innovation Solution
A one-stage method using electrospinning to integrate a multilayer polymer cuff with a metal stent, where the cuff's wall thickness gradient allows seamless transformation into valve leaflets, enhancing fatigue resistance and biocompatibility, utilizing biostable polymers like aromatic polycarbonate urethanes and polycarbonate silicones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate formation and connection of valve leaflets and stent sealing is used, then manufacturing flexibility is maintained, but production time increases and human error occurs
Solution Approach 1:
The patent merges the previously separate manufacturing processes of valve leaflets and stent sealing into a single integrated electrospinning process. The multilayer polymer cuff is formed in one continuous operation that simultaneously creates both the leaflet portion and the stent sealing portion, eliminating the need for separate formation and connection steps. This integration directly reduces production time and eliminates human error associated with manual assembly operations.
Solution Approach 2:
The patent applies preliminary action by pre-forming the complete multilayer polymer cuff structure with integrated leaflet and sealing portions in a single electrospinning process before any assembly operations. The gradient wall thickness is established during the initial manufacturing stage, preparing the structure for subsequent automated attachment to the stent without requiring manual intervention for thickness adjustments or sealing modifications.
2Productivity
If separate formation and sewing connection of components is used, then manufacturing precision can be controlled, but the process becomes costly and time-consuming
Solution Approach 1:
The patent combines multiple manufacturing operations into a single electrospinning process that simultaneously forms the multilayer polymer cuff with gradient wall thickness, creates the leaflet structure, and prepares the stent sealing interface. This merging eliminates the need for separate formation and sewing operations, significantly improving production efficiency while reducing manufacturing complexity through process integration.
Solution Approach 2:
The patent utilizes parameter changes in the electrospinning process to achieve different structural characteristics within the single multilayer cuff. By varying electrospinning parameters (voltage, flow rate, distance) during different stages of cuff formation, the process creates regions of different wall thicknesses and material properties appropriate for leaflets versus stent sealing, all within one continuous manufacturing operation.
3Reliability
If polyurethane materials are used for prosthetic valves, then biocompatibility is achieved, but long-term biostability and thrombosis resistance are compromised
Solution Approach 1:
The patent employs composite materials by formulating the multilayer polymer cuff from biostable polymer compositions that incorporate thrombosis-resistant properties. The electrospinning process deposits layers of polymers selected for their long-term biostability in the cardiovascular environment, replacing traditional polyurethane materials that degrade over time. The composite structure maintains biocompatibility while adding resistance to thrombosis and material degradation.
Solution Approach 2:
The patent applies local quality by creating regions with different material properties within the multilayer cuff structure. The gradient wall thickness and varied layer compositions are tailored to specific locations: thinner, more flexible regions for leaflet function versus thicker, more robust regions for stent sealing. This localized optimization ensures both biostability and thrombosis resistance where most critical while maintaining overall valve functionality.
4Strength
If uniform wall thickness cuff is manufactured, then structural simplicity is maintained, but fatigue strength at integration points is reduced
Solution Approach 1:
The patent applies local quality by implementing a gradient wall thickness profile in the multilayer polymer cuff, where the wall thickness varies continuously from the leaflet attachment region through the stent integration zone to the distal end. This gradient structure concentrates material and structural reinforcement precisely at the stent integration points where fatigue strength is most critical, while maintaining thinner walls in regions where flexibility is prioritized. The localized thickening at integration points directly enhances fatigue resistance without requiring uniform thickening throughout the entire cuff.
Solution Approach 2:
The patent transitions from a uniform one-dimensional wall thickness design to a multi-dimensional gradient structure. The wall thickness varies along the longitudinal axis of the cuff, creating a continuous dimensional transition that optimizes mechanical properties at different locations. This dimensional change allows the structure to accommodate varying stress conditions along its length, with enhanced thickness at high-stress integration zones while maintaining overall structural elegance and functionality.
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
This method simplifies the production process, reduces manual labor, ensures precise dimensions and mechanical parameters, and improves the biocompatibility and durability of the prosthetic heart valve, minimizing thrombogenicity and material degradation.
Implementation Method 1
the technique of electrospinning. Thickening of the cuff wall in the place of integration, which is obtained according to the method, strengthens and increases fatigue strength of the flexible part
Data Source
AI summary
A method of forming prefabricated units used in production of systems of prosthetic aortic valve transcatheter implantation and prosthetic aortic valve prefabricated unit with an non-thrombogenic smooth surface layer or with a porous fibrous layer constituting a scaffold for epithelium cell culture, intended for manufacturing TAVI system. Stents for covering and solutions of polycarbonate silicones and/or polycarbonate urethanes and/or polyurethane with average molecular weight in the range from 50,000 g/mol to 200,000 g/mol in the solvent DMAC are prepared. Initially a smooth layer of polycarbonate silicone is applied in the electrospinning machine by electro spraying with use of the solution in DMAC with the concentration of 2-8% w/w. and/or a fiber of polycarbonate urethane is applied by electrospinning on the roller with use of the solution in DMAC with the concentration of 8-20% w/w to obtain the first surface layer, with a specified speed, number of heads, thickness of capillaries, speed of movement, voltage and distance between the capillary and the roller and the specified flow of the solution on the feeding pump and after a certain time the layer covering the roller with thickness of 1-100 μm is obtained. Thereafter the inner intermediate layer of polycarbonate silicone is formed by electro spraying. When the thickness of the layer is approximately 5 to 100 μm the process is stopped and stents are placed on the formed layer and similarly like applying the former intermediate layer the application of the inner intermediate layer is continued on the whole length of the roller. Thereafter the final surface layer is applied like the first surface layer until a prefabricated unit with the polymer material thickness from 50 to 250 μm is obtained.