ESEM–EDX Investigation of the Cross-sectional Microstructure and Elemental Chemical Composition of a Giant Human Cardiac Calculus

We used environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray (EDX) microanalysis to study the microstructure topography and elemental composition of a cross section of a giant human cardiac calculus after cutting it in half. The giant cardiac calculus was isolated from an 80-year-old male patient after invasive open heart surgery. After treatment with formalin, the yellow-brown fist-shaped calcareous wet mass, 50 mm × 45 mm × 30 mm in size, became a brown-yellow hard calculus and was surrounded by a thick white tissue layer. The dissection of the whole cardiac calculus into two halves clearly revealed a dense layer on the encrusted surface and a bread-like texture of the internal structure of the calculus. The cross-sectional ESEM micrograph of the cardiac calculus illustrated that different agglomerates were deposited on the uneven petrous surface. The EDX spectra and elemental chemical mapping revealed that C and O were the major elements on the surface of the different irregular, near-spherical agglomerates with trace amounts of N, Na, P, and Ca, whereas the petrous surface showed higher amounts of C, O, P, and Ca, as well as trace amounts of N and Na. These elemental compositions were consistent with the surface microstructure analysis results, which showed that the agglomerates were mainly composed of cholesterol, and the petrous surface was mainly composed of calcium hydroxyapatite, as confirmed by our previous Raman spectroscopic detection. This study indicates that ESEM–EDX microanalysis may directly provide useful information about microstructural characteristics and the spatial distribution of elements on a cross-sectional surface of a halved cardiac calculus.