The mosaic bioprosthesis in the aortic position: Hemodynamic performance after 2 years

Background. The Mosaic bioprosthesis is a porcine valve combining several n ew features to improve hemodynamics and durability: a low profile stent for reduced flow obstruction, zero pressure fixation to maintain the natural c ollagen crimp, and the amino oleic acid antimineralization treatment to enh ance durability. Methods. Fifty-five Mosaic valves were implanted in the aortic position sin ce February 1994. Data from these patients (group 1) were compared with dat a from 52 patients who had received a Hancock Modified Orifice II aortic va lve (group 2). The mean patient age was 72.0 (+/- 5.9) years for group 1 an d 76.8 (+/- 4.7) years for group 2. Clinical examinations including transth oracic echocardiography were performed 6 and 24 months postoperatively. Results. Mild aortic insufficiencies were found in 2 patients in group 1 an d in 3 patients in group 2. There were no embolic or bleeding complications . One Mosaic patient required reoperation due to mitral insufficiency. Duri ng the reoperation, a small (approximate to 3 mm) thrombus was noted on the outflow side of a Mosaic cusp. The valve was removed and replaced prophyla ctically. In the 2-year follow-up, hemodynamic measurements showed mean pre ssure gradients of 12.4 mm Hg for the 21 mm, 11.3 mm Hg for the 23 mm, and 15.4 mm Hg for the 25 mm prostheses in the Hancock group. In the Mosaic gro up, mean pressure gradients were 14.8 mm Hg for the 21 mm, 10.9 mm Hg for t he 23 mm, and 11.5 mm Hg for the 25 mm valves. Differences between pressure gradients and effective orifice areas of the Hancock and the Mosaic valves were not statistically significant. Early mortality in group 1 was 3.6% an d in group 2 3.8%. Overall mortality was 12.7% and 13.5%, respectively. Conclusions. The Mosaic valve has low pressure gradients for all sewing rin g diameters. Compared with the Hancock Modified Orifice valve, there was no statistically significant gradient difference but a tendency toward better hemodynamics was noted in the Mosaic group after 2 years. (C) 1998 by The Society of Thoracic Surgeons.