Stress strain characteristics of glutaraldehyde treated porcine aortic valve tissue following ethanol treatment

Background: Glutaraldehyde treatment of heterologous tissue valves is necessary to improve their durability. Anti-calcification treatment is required following glutaraldehyde fixation for tissue valves, to prevent bioprosthetic valve dysfunction due to degenerative changes. One of the simpler anti-calcification strategies utilises ethyl alcohol, and this has been shown to be highly effective. However, whether this treatment has an effect on the physical characteristics has not been studied. Present study was planned to evaluate the physical characteristics of the porcine aortic valve cusps using a Shimadzu AGS 500 G stress/strain tester. Methods and Material: Porcine hearts were obtained from abattoir. The tube of aorta with the valve was dissected and washed in normal saline. The untreated cusp provided the control (C) and the glutaraldehyde treated cusp(G) and the ethanol treated cusp following glutaraldehyde fixation (G+A) were the test samples. These three cusps belonged to the same aortic valve. Uni-axial Stress/strain testing in the circumferential direction was done on a Shimadzu AGS 500 G stress/strain tester. The three groups were compared by analysis of variance for significant difference. Wherever this test suggested the possibility, an unpaired 't' test was applied. Results: There was significant difference between the groups (C), (G+A) for the parameter maximum load (p=0. 002). For the parameter maximum stress, there was significant difference between the groups (G+A) and both groups (G) and (C), the p value being 0. 047 and 0. 007 respectively. The group (G+A) also showed increased ability to elongate on stress, (maximum displacement), as compared to both groups(G) and (C)(p=0. 025 and p=0. 049 respectively). The group(G+A) also showed significantly higher maximum strain as compared to both groups (G) and (C){p=0. 006 and p=0. 027 respectively}. Among the parameter unrelated to stress or strain, there was significant difference between means for parameter Energy for group (G+A) and both (G) & (C). The values being p<0. 001 and p=0. 001 respectively. Conclusion: The tensile strength of ethanol treated glutaraldehyde fixed cusps was significantly higher than the control and their ability to elongate on stress was also greater than both the control and glutaraldehyde treated groups. © 2004 Indian Association of Cardiovascular-Thoracic Surgeons.