Premium
Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy
Author(s) -
DELOGNE CHRISTOPHE,
LAWFORD PATRICIA V,
HABESCH STEVEN M,
CAROLAN VIKKI A
Publication year - 2007
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.2007.01824.x
Subject(s) - octacalcium phosphate , environmental scanning electron microscope , scanning electron microscope , fourier transform infrared spectroscopy , raman spectroscopy , infrared spectroscopy , chemistry , infrared microscopy , spectroscopy , phosphate , carbonate , analytical chemistry (journal) , mineralogy , materials science , infrared , chemical engineering , physics , organic chemistry , optics , quantum mechanics , chromatography , engineering , composite material
Summary Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X‐ray micro‐analysis, X‐ray diffraction, Fourier‐transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma–optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X‐ray micro‐analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier‐transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as β‐tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.