Structural analysis of calcified aortic valve deposits by microtomography

Aims Mineralization is a physiological process, which consists in the deposition of minerals in an organic matrix. Minerals are composed mainly of calcium phosphate (hydroxyapatite crystals). Mineralization is a complex and multistage process requiring an interaction of many physicochemical factors. The mechanism responsible for deposition of minerals has not been fully elucidated, yet. Mineralization can be a pathological process, when it develops outside osseous tissue. Mineralization in aortic valves (AVs) is an example of such process. Degree of AV mineralization depends on many features, including the characteristics of the valve itself. It is commonly accepted [1] that the first stage of the aortic valve calcification requires the precipitation of small mineral seeds within tissue structures. Next, the seeds grow and ripen that leads to the massive mineralization and to the valve destruction. A number of factors, alone or in synergy, may contribute in the initiation and further development of the process. A large number of anti-calcification treatments have been tested [2]. Until now, however, no method has proven its efficacy in clinical applications [3]. Recent data suggest that soft tissue mineralization is a process similar to osteogenesis [4]. Therefore, some authors proposed the hypothesis that soft tissue mineralization and bone calcification may be influenced by similar factors. Many studies have been conducted to investigate chemical composition of mineralized AV cusps [5,6]. Microtomography offers unique capabilities for studies of localization, shape and distribution of calcified deposits in aortic valve cusps. Results obtained with this method can provide a key link between the type of calcified deposits and specific pathologies of aortic valves.