Abstract
Natural and bioprosthetic heart valves suffer from calcification, despite their differences in etiology and tissue material. The mechanism of developing calcific deposits in valve tissue is still not elucidated. The calcific deposits developed on human natural and bioprosthetic heart valves have been investigated and compared by physicochemical studies and microscopy investigations and the results were correlated with possible mechanisms of mineral crystal growth. Deposits from 16 surgically excised calcified valves (seven natural aortic and nine bioprosthetic porcine aortic valves) were examined by chemical analysis, FTIR, XRD, and SEM-EDS. The Ca/P molar ratio of the deposits from bioprosthetic valves (1.52±0.06) was significantly lower compared to that of the natural valves (1.83±0.03) (p=0.05, 1-way ANOVA). SEM-EDS examination of the two types of valve deposits revealed the coexistence of large (>20 μm) and medium (5–20 μm) plate-like crystals as well as microcrystalline (<5 μm) calcium phosphate mineral formations. The results confirmed the hypothesis that the mineral salt of calcified valves is a mixture of calcium phosphate phases such as dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP). DCPD and OCP are suggested to be precursor phases transformed to HAP by hydrolysis. The lower value of the Ca/P molar ratio found in the bioprostheses, in comparison with that corresponding in natural valves, was ascribed to the higher content in these deposits in precursor phases DCPD and OCP which were subsequently transformed into HAP. On the basis of chemical composition of the deposits and their morphology it is suggested that crystal growth proceeds in both types of valves by the same mechanism (hydrolysis of precursor phases to HAP) in spite of their differences in etiology, material, and possible initiation pathways.
Similar content being viewed by others
References
F. J. Schoen and R. J. Levy, J. Card. Surg. 9(Suppl) (1994) 222.
F. J. Schoen and R. J. Levy, J. Biomed. Mater. Res. 47(4) (1999) 439.
M. P. Sands, E. A. Rittenhause, H. Mohri and K. A. Merendino, Ann. Thorac. Surg. 8(5) (1969) 407.
D. J. Schneck, in “The Biomedical Engineering Handbook” (CRC Press, Boca Raton, Fla, 1995) p. 3.
G. H. Nancollas, in “Biomineralization” (VCH, Weinheim, 1989) p. 157.
B. B. Tomazic, W. D. Edwards and F. J. Schoen, Ann. Thorac. Surg. 60(2 Suppl) (1995) 322.
J. Kapolos, D. Mavrilas, Y. F. Missirlis and P. G. Koutsoukos, J. Biomed. Mater. Res. (Appl. Biomater.) 38 (1997) 183.
B. B. Tomazic, L. C. Chow, C. M. Carey and A. J. Shapiro, J. Pharmaceut. Sci. 86(12) (1997) 1432.
D. Mavrilas, A. Apostolaki, J. Kapolos, P. J. Koutsoukos, M. Melachrinou, V. Zolota and D. Dougenis, J. Crystal Growth 205(4) (1999) 554.
B. B. Tomazic, W. E. Brown and F. J. Schoen, J. Biomed. Mater. Res. 28 (1994) 35.
F. J. Schoen, H. Harasaki, K. H. Kim, H. C. Anderson and R. J. Levy, J. Biomed. Mater. Res: Appl. Biomater. 22 (1988) 11.
J. P. Barone and G. H. Nancollas, J. Colloid and Interface Sci. 62 (1977) 421.
W. E. Brown, J. R. Lehr, J. P. Smith and A. W. Frazier, J. Amer. Chem. Soc. 79 (1957) 5318.
G. H. Nancollas and M. S. Mohan, Arch. Oral. Biol. 15 (1970) 731.
J. R. Lehr, W. E. Brown and E. H. Brown, Soil Sci. Amer. Proc. 23 (1959) 3.
B. B. Tomazic, W. E. Brown and E. D. Eanes, J. Biomed. Mater. Res. 27 (1993) 217.
N. B. Michelson, Anal. Chem. 29 (1975) 60.
J. Kapolos and P. G. Koutsoukos, Langmuir 15 (1999) 6557.
M. D. Francis and N. C. Webb, Calcif. Tissue. Res. 6 (1971) 335.
I. Zipkin, in “Biological Calcification: Cellular and Molecular Aspects” (Appleton Century Crofts, New York, 1970) p. 69.
W. F. Neuman and M. W. Neuman, Chem. Rev. 53 (1953) 1.
W. F. Neuman, Amer. Inst. Oral. Biol. Annu. Meet. 28 (1971) 115.
B. S. Strates, W. F. Neuman and G. L. Levinskos, J. Am. Chem. Soc. 61 (1957) 279.
Z. Amjad, P. G. Koutsoukos, M. B. Tomson and G. H. Nancollas, J. Dent. Res. 57 (1978) 909.
E. D. Eanes, I. H. Gilessen and A. S. Posner, Nature 208 (1965) 365.
J. D. Termine, R. A. Peckauskas and A. S. Posner, Arch. Biochem. Biophys. 140 (1970) 318.
L. Brecevic and H. Milhofer Furedi, Calcif. Tissue. Res. 10 (1972) 82.
V. J. Ferrans, S. W. Boyce, M. E. Billingham, M. Jones, T. Ishihara and W. C. Roberts, Am. J. Cardiol. 46,5 (1980) 721.
G. H. Nancollas, in “Phosphate Minerals” (Springer Verlag, Berlin, 1984) p. 137.
Y.-S. Lee, J. Electron Microsc. 42 (1993) 156.
F. Betts, N. C. Blumenthal and A. S. Posner, J. Crystal Growth 53 (1981) 63.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Mikroulis, D., Mavrilas, D., Kapolos, J. et al. Physicochemical and microscopical study of calcific deposits from natural and bioprosthetic heart valves. Comparison and implications for mineralization mechanism. Journal of Materials Science: Materials in Medicine 13, 885–889 (2002). https://doi.org/10.1023/A:1016556514203
Issue Date:
DOI: https://doi.org/10.1023/A:1016556514203