The influence of stenting on the behavior of amino-oleic acid-treated, glutaraldehyde-fixed porcine aortic valves in a sheep model

Background and aim of the study: The durability of freehand-sewn aortic val ve homografts used for valve replacement in humans is greater than for sten ted aortic homografts. In analogy with this, it is expected that the durabi lity of a stentless heterograft will be superior to that of its stented cou nterpart. Our objective was to investigate the influence of stenting on ami no-oleic acid (AOA)-treated, glutaraldehyde-fixed porcine aortic valve biop rostheses. Methods: Twelve young sheep underwent implantation of porcine aortic valves in the pulmonary artery: six porcine aortic stentless valves (Freestyle(R) ) and six porcine aortic stented valves (Mosaic(R)). In each series, three valves were explanted after three months, and three after six months. Valve s were analyzed by gross inspection, radiography, histology, and transmissi on electron microscopy. Quantitative determination of calcium content was m ade with atomic absorption spectrometry. Results: The porcine aortic stentless valve showed extensive calcification of its aortic wall portion, but had perfectly functioning, pliable cusps wi thout calcification up to six months. The cusps of porcine aortic stented v alves were also pliable and functioning without calcification up to six mon ths. Only minimal calcification was seen in the aortic wall of the stented valves. At six months after implantation the cusps of stentless valves cont ained significantly less calcium than those of stented valves (2.7 +/- 1.2 mu g/mg and 7.9 +/- 2.3 mu g/mg, respectively; p = 0.011). However, the aor tic wall from stentless valves contained significantly more calcium than th at of stented valves (three-month explants: 39.2 +/- 14.4 versus 7.2 +/- 2. 8 mu g/mg; p < 0.05; six-month explants: 49.3 +/- 14.0 versus 14.1 +/- 5.9 pg/mg; p < 0.05). Conclusion: These data suggest that stenting does influence cuspal calcific ation of AOA-treated, glutaraldehyde-fixed porcine aortic valves.