Crystallochemical characteristics of the inorganic phase of human calcific aortic valvar stenosis.

Abstract

To determine the elemental composition of the mineral deposits found in human calcific aortic valvar stenosis and to verify by x ray diffraction crystal class previously reported by electron diffraction 138 quantitative energy dispersive analyses and x ray diffraction of pooled specimens were performed on samples of aortic valves excised from 12 patients. The principal components of the calcified portions of the valves were 38.15% calcium and 17.68% phosphorus. The weight percentage calcium to phosphorus ratio was 2.16 and an elemental distribution related to the simplest ideal unit cell formulation Ca10(PO4)6(OH)2 was determined as: (Ca0.952Mg0.044Na0.097K0.005)10 (P0.952S0.025C0.023)6O23.96(Cl0.0184O0. 982H)2. The hexagonal unit cell was found to have an a axis of 9.424 A(0.9424 nm); c axis of 6.787 A(0.6787 nm); volume of 522 A3(0.522 nm3); and density of 3.2 g.cm-3. On the bases of the composition, the axial dimensions, and the density the material was classified as the dahllite form of apatite. There was no evidence of crystalline cholesterol. Variations in elemental composition showed no significant correlation with age or sex of the patient; statistically, neither the cusp involved nor the location on the leaflet affected the mineral composition.