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PAGE Investigation of the Surface Chemistry of Heart Valves by FTIR and Raman Spectroscopy.
C.Delogne1, V.A Carolan2, M Clench2, P Lawford3, J Yarwood1.
1Materials Research Institute, Howard Street, Sheffield S11WB, United Kingdom.
2School of Sciences and Mathematics, Sheffield Hallam University, City Campus, Sheffield S11WB, United Kingdom.
3Department of Medical Physics, Floor I, Royal Hallamshire Hospital, Glossop Road, Sheffield S102JF, United Kingdom.
At the turn of the new millenium, the main medical causes of death are cancer and heart
disease. Almost 30% of deaths are due to the cardiovascular diseases and these represent
the major cause of mortality in Europe. Heart valve disease accounts for an appreciable
number of these deaths.
Diseased heart valves have been replaced in surgery for almost fifty years. Two basic types of artificial replacements are used routinely: mechanical and bioprosthetic heart valves. There is a great interest in the latter, due to surgeons incurring problems with mechanical heart valves, as patients require long-term anticoagulant treatment. Porcine aortic valve xenografts and bovine pericardial valve tissue are used as bioprosthetic valves. Both of these consist of xenogeneic tissue (predominantly collagen), which is treated with low concentrations of glutaraldehyde during their manufacture, so that the immunogenicity is significantly reduced. However, this induces a degeneration process: products of the glutaraldehyde treatment are thought to be involved in the accumulation of calcium phosphate in the in vivo heart valves, leading to the partial or total blockage of these.
Many aspects of the bioprosthetic heart valve treatment, including the chemistry of glutaraldehyde, are still poorly understood. Therefore, it is proposed to characterise the surface chemistry of glutaraldehyde-treated valve tissue using various analytical techniques. For this purpose, a series of model systems was first examined to obtain fundamental data from this type of surface.
The experiments performed so far have shown FTIR and Raman to be useful non destructive techniques for characterising the surface chemistry of heart valves. The information obtained from model compounds reacted with glutaraldehyde is complementary to that from other techniques such as NMR or mass spectrometry.
Key Words: Heart valve, Glutaraldehyde, FTIR, Raman, e -amino-n-caproic acid.