Measurement and reconstruction of the leaflet geometry for a pericardial artificial heart valve

Bioengineering Strategies for Polymeric Scaffold for Tissue Engineering an Aortic Heart Valve: An Update

The occurrence of dysfunctional aortic valves is increasing every year, and current replacement heart valves, although having been shown to be clinically successful, are only short-term solutions and suffer from many agonizing long-term drawbacks. The tissue engineering of heart valves is recognized as one of the most promising answers for aortic valve disease therapy, but overcoming current shortcomings will require multidisciplinary efforts. The use of a polymeric scaffold to guide the growth of the tissue is the most common approach to generate a new tissue for an aortic heart valve. However, optimizing the design of the scaffold, in terms of biocompatibility, surface morphology for cell attachments and the correct rate of degradation is critical in creating a viable tissue-engineered aortic heart valve. This paper highlights the bioengineering strategies that need to be followed to construct a polymeric scaffold of sufficient mechanical integrity, with superior surface morphologies, that is capable of mimicking the valve dynamics in vivo. The current challenges and future directions of research for creating tissue-engineered aortic heart valves are also discussed.

A parametric study on mathematical formulation and geometrical construction of a stentless aortic heart valve

This study presents a novel methodology for constructing an accurate geometrical model of a stentless aortic heart valve replacement (AVR). The main objective is to propose an optimized AVR model that can be used as an ideal scaffold for tissue engineering applications or a biocompatible prosthesis. Current techniques available for creating heart valve geometry, including leaflets, are very complicated and are not precise, due to the extensive use of various complicated parameters. This paper introduces an alternative design procedure that uses limited and effective numbers of controlling parameters to construct the whole valve including the sinus of valsalva. In doing so the hyperbolic curves for multithickness leaflets are used and a 3D elliptical formulation is incorporated for the surface geometry of the sinus of valsalva. Still, the feasibility and the precision of the mathematical method are established by performing standard deviation analysis on the constructed surfaces. The surface fitting residuals are found as low as error 0.2351 mm with standard deviation of 8.83e-5 over the commissural lines. Preliminary validation to the proposed AVR model performance is achieved by testing the generated AVR model under quasi static condition while obtaining the mesh independent setup. The numerical model showed a rapid response of the leaflets to the transvalvular pressure where adequate values of stress are measured over the commissural lines.

Rapid prototyping for biomedical engineering: current capabilities and challenges

A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends.

Biocomposites of nanohydroxyapatite with collagen and poly(vinyl alcohol)

Biocomposites of hydroxyapatite, HAp, in conjunction with various binders including poly(vinyl alcohol), PVA, and collagen have the potential of serving in various tissue engineering applications, such as in bone repair and reconstruction tasks, especially if the nanoparticles of hydroxyapatite are used. Here, hydroxyapatite nanoparticles (n-HAp) were synthesized at the ultimate size range of 10-50 nm and then incorporated into PVA or in situ synthesized in collagen/PVA. The biocomposites of HAp with PVA exhibited relatively high elasticity (as revealed by the linear viscoelastic material functions, characterized upon small-amplitude oscillatory shear) especially upon cryogenic treatment. The incorporation of the collagen into the PVA/HAp biocomposite provided internal porosity to the biocomposite with the pores in the 50-100 nm range for collagen/HAp and 50-500 nm for the collagen/HAp/PVA.