Is 10 minutes the optimum immersion time in 0.6% glutaraldehyde for human pericardium?

Pericardial fixation with 0.6% glutaraldehyde is usually assessed by measuring the shrinkage temperature of the tissue: the higher the shrinkage temperature, the greater the degree of cross-linking induced between collagen molecules. Animal pericardium studies have shown maximum response to be obtained after brief immersion (10 min). Our aim was to evaluate the effect of glutaraldehyde immersion time on shrinkage temperature of human pericardium which, to our knowledge, has not yet been studied.

Pericardial strips were harvested from 40 patients undergoing cardiac surgery. Time of immersion in glutaraldehyde ranged from 3 min to 6 months. Fresh untreated human pericardium samples were used as controls. The relationship between shrinkage temperature and time of treatment with glutaraldehyde was studied using a regression analysis.

Glutaraldehyde treatment of pericardial tissues caused an increase in shrinkage temperature that was related biphasically to the time of immersion in glutaraldehyde. Mathematical expression of this curve permitted glutaraldehyde immersion time to be evaluated in relation to the degree of optimal shrinkage temperature. The time required for optimal fixation with glutaraldehyde, as measured by shrinkage temperature, was 100+/-0.77 min.

Our results suggested that a 10-min exposure to glutaraldehyde was insufficient for 'correct' fixation of human pericardium. Inadequate glutaraldehyde exposure of human pericardium may explain mid and long-term failures reported with this tissue in cardiac surgery.