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J Thorac Cardiovasc Surg 1997;114:512
© 1997 Mosby, Inc.

LETTERS TO THE EDITOR

Concentration of glutaraldehyde in fixation of bioprosthetic values

Department of Cardiovascular Surgery
Akita University School of Medicine
Akita 010, Japan

To the Editor:

We read with great interest the article by Duncan, Boughner, and Vesely, ¹ in which they concluded that better stabilization of the porcine aortic valve can be achieved if the tissue is fixed dynamically in glutaraldehyde solution. Dynamic fixation stabilizes the tissue within 3 hours 15 minutes and 24 hours when the porcine aortic valves are cross-linked in 0.5% and 0.05% glutaraldehyde, respectively, at room temperature. ¹ Schoen, Tsao, and Levy ² have noted that complete glutaraldehyde uptake by bioprosthetic tissue occurs within 24 hours of incubation. However, it was observed that complete glutaraldehyde uptake by bioprosthetic tissue did not occur even in 1 month after the onset of treatment when the tissue was preserved in glutaraldehyde solution of a particular concentration. ³ When a tissue is exposed to glutaraldehyde solution of a particular concentration for a certain period, it becomes resistant to further penetration of glutaraldehyde molecules from the solution of a particular concentration. At this stage a slight increase in the concentration of glutaraldehyde in the preservative solution is enough for further access of glutaraldehyde molecules to the interstitium of the tissue, which may be documented by measuring the concentration of glutaraldehyde of the preservative solution before and after treatment. However, a sharp increase in concentration of glutaraldehyde in the preservative solution may falsely indicate the completion of saturation of the tissue with glutaraldehyde after two or three changes owing to rapid interaction with the outer surface of the tissue, and this event may impair the further penetration of glutaraldehyde molecules. ³ We found that complete stabilization can be attained by preserving the tissue in glutaraldehyde solution with gradual increases in concentrations from 0.1% to 0.25% at 4° to 10° C for more than 8 weeks. During cross-linking of the tissue in glutaraldehyde, we checked the concentration of glutaraldehyde in the preservative solution every seventh day and compared it with that of fresh solution spectrophotometrically after reacting with -aminocaproic acid. Because the concentration of glutaraldehyde was found to decrease in the preservative solution after the onset of preservation, the concentration of glutaraldehyde in the preservative solution was increased gradually up to 0.25% over a period of more than 8 weeks, until the concentration was the same as that of the fresh solution. ^3,4 However, this period was less than 4 weeks when the cross-linking was carried out at 37° C. ⁵ According to our procedure, the cross-linking process of a tissue itself dictates the required concentration of glutaraldehyde and duration of the process at a particular temperature.

The authors ¹ presume that, with their technique, there is a possibility of limitation of calcification of glutaraldehyde-treated bioprosthetic valves (see Conclusion). Dynamic fixation of bioprosthetic valves in glutaraldehyde may promote a better cross-linking process; however, our previous experience ^3,4,6 suggests that, short-term or prolonged, adequate or inadequate fixation would never change the pathologic feature of calcification of bioprostheses when only glutaraldehyde treatment is concerned.

12/8/83229

References

1. Duncan AC, Boughner D, Vesely I. Viscoelasticity of dynamically fixed bioprosthetic valves. II. Effect of glutaraldehyde concentration. J Thorac Cardiovasc Surg 1997;113:302-10. [Abstract/Free Full Text]
   
2. Schoen FJ, Tsao JW, Levy RJ. Calcification of bovine pericardium used in cardiac valve bioprostheses: implications for the mechanisms of bioprosthetic tissue mineralization. Am J Pathol 1986;123:134-45. [Abstract]
   
3. Chanda J. Anticalcification treatment of pericardial prostheses. Biomaterials 1994;15:465-9. [Medline]
   
4. Chanda J. Prevention of calcification of heart valve bioprostheses: an experimental study in rat. Ann Thorac Surg 1995;60:S339-42.
   
5. Chanda J, Kuribayashi R, Abe T. New-generation valved conduit. J Thorac Cardiovasc Surg. In press.
   
6. Chanda J, Rao SB, Mohanty M, et al. Calcification prevention of tissue valve. Artif Organs 1994;18:752-57.[Medline]
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chanda, J. Articles by Abe, T. Search for Related Content PubMed PubMed Citation Articles by Chanda, J. Articles by Abe, T.