Antialcification Treatments of Bioprosthetic Pericardial Heart Valve Tissue: a Comparative Experimental StudyPaul Herijgers
, Herbert De Praetere, Aziza Yakubova, Wouter Oosterlinck, Abdelmotagaly Elgalad, Peter Verbrugghe, Willem Flameng, Bart Meuris
Research Unit Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium
OBJECTIVE: In a long term clinical follow-up study, we recently demonstrated that anticalcification treatment of bioprosthetic heart valves delayed the onset of structural valve deterioration. Several anticalcification treatments are currently used in pericardial bioprostheses. It is unknown whether all these anticalcification treatments are equally effective. Improvements in anticalcification techniques should be evaluated in comparison with existing treatments. Therefore, we decided to perform a direct comparative study on pericardial patches with anticalcification treatments applied in commercially available bioprostheses and compared them with standard glutaraldehyde treated patches.
METHODS: Three times nine patches of equal size featuring standard fixation with glutaraldehyde and one of the following anticalcification treatments: 1) PRT (featured by Mitroflow Crown PRT, Sorin, Italy), 2) Linx AC (featured by Trifecta, St Jude Medical, USA), 3) ThermaFix (featured by Perimount Magna, Edwards Lifesciences, USA) were subcutaneously implanted for 60 days in rats of 4 weeks old. Nine additional patches of untreated bovine pericardium fixed in glutaraldehyde according to the standard procedure were implanted as controls. After macroscopic evaluation, the patches were analyzed with soft X-Rays to study calcification. Afterwards, half of the patch was analysed histologically. Calcium content was quantified in the other half of the patch. Statistical analysis was performed with Statistica 8 (Statsoft, USA).
RESULTS: No signs of infection were present. Control patches exhibited irregular, white indurations. Patches from all treated groups were supple without indurations. X-Rays revealed extensive calcification of the control patches, but not in the three groups with anticalcification treatment. Calcium content was significantly higher in the control group (geometric mean [95% confidence interval]) of 5.81 [1.13-29.88] µg Ca2+/mg dry weight versus 0.58 [0.34-0.98] µg/mg for PRT, 0.65 [0.45-0.92] µg/mg for Linx AC, and 0.86 [0.72-1.03] µg/mg for the Thermafix group (Kruskal-Wallis, p=0.038, with control higher than each treated group with post-hoc test). The three groups with anticalcification treatment did not differ significantly. Histology confirmed the presence of calcified regions in the patch in the control group, but not in the treated groups. Remarkable is the large variation in calcium accumulation in the patches without anticalcification treatment, but not in the treated ones.
CONCLUSIONS: Current anticalcification treatments after glutaraldehyde fixation of pericardial patches reduce calcium accumulation predictably when implanted in a subcutaneous rat model. This allows a more accurate prediction of the durability of a bioprosthesis, potentially reducing the degree of uncertainty in patient counseling before the operation.Keywords:
heart valve, anticalcification treatment, bioprosthesis, experimental study, rat, pericardium