Background: Bioprosthetic heart valves still suffer from calcification. In the department of Cryobiology & Biomaterials, we have established an in vitro calcification test method which is suitable for the investigation of calcification patterns of heart valves. In a modified test protocol we use the pH-dependency of the calcification process to control and stabilise the process by keeping the calcification ions more constant than in the established test protocol. Methods: Five glutaraldehyde-fixed porcine heart valve bioprostheses underwent accelerated dynamic in vitro calcification individually. Three valves were tested according to the established test protocol. Two valves were studied with the new pH-controlled loop system. pH drop was used as an index for the consumption of the calcification ions. The degree of calcification was determined by means of lX-ray (high resolution x-ray on mammography machine), conventional and micro computer tomography (CT, l-CT). Results: We determined the average degree of calcification after 12 million cycles. The value was calculated to be 12 % vs. 67 % (established vs. pH-controlled group) using lX-ray (2D), 3 % vs. 16 % using CT, and 3 % vs. 33 % using l-CT. Conclusion: A new faster and more potent in vitro calcification method has been developed. Optimisation of this pH-controlled method in order to implement an additional direct calcification ion concentration control is under construction.Keywords:In vitro calcification, biological heart valve prostheses, pH-value control
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