Natural and prosthetic heart valve calcification: morphology and chemical composition characterization.

Calcification is the most common cause of damage and subsequent failure of heart valves. Although it is a common phenomenon, little is known about it, and less about the inorganic phase obtained from this type of calcification. This article describes the scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy and Ca K-edge X-ray absorption near edge structure (XANES) characterization performed in natural and bioprosthetic heart valves calcified in vivo (in comparison to in vitro-calcified valves). SEM micrographs indicated the presence of deposits of similar morphology, and XANES results indicate, at a molecular level, that the calcification mechanism of both types of valves are probably similar, resulting in formation of poorly crystalline hydroxyapatite deposits, with Ca/P ratios that increase with time, depending on the maturation state. These findings may contribute to the search for long-term efficient anticalcification treatments.

Lyophilized bovine pericardium treated with a phenethylamine-diepoxide as an alternative to preventing calcification of cardiovascular bioprosthesis: preliminary calcification results.

This study investigated the calcification process that occurred on chemically treated bovine pericardium substrata through tests with simulated body fluid solutions. The use of bovine pericardium bioprosthetic valves in heart valve surgery has a significant drawback due to the calcification processes. Thus, many routes such as chemical treatments in the substratum or the adoption of systemic therapies are considered in the literature with the intention to inhibit or to decelerate this process. The presented treatment using the two different phenetylamine-diepoxide solutions showed no effects on calcification experiments as showed by the tests. However, the lyophilized bovine pericardium samples, treated with both solutions, did not show any detectable phosphate deposits. The lyophilization of bovine pericardium before chemical treatments with cross-link agents as epoxy compounds may be an alternative to the conventional calcification prevention methods, but further investigations are recommended to check if the same behavior is found in all lyophilized systems.