Hemodynamic features of the freestyle aortic bioprosthesis compared with stented bioprosthesis

Background. The Freestyle prosthesis is a new stentless aortic bioprosthesis. Anticipated benefits are improved hemodynamics and increased longevity. Methods. Doppler echocardiograms were performed early and at 3 to 6 months, 1 year, and 2 years after operation in 157 patients (69 men, 88 women, aged 48 to 85 years) with this prosthesis, and results were compared with hemodynamic data in patients with Intact and Mosaic stented bioprostheses. Results. Distinctive features of the prosthesis compared with stented prostheses are (1) an increase in effective orifice area (+0.15 +/- 0.26 cm(2); p < 0.05) and a decrease in mean gradient (-3.5 +/- 4.0 mm Hg; p < 0.001) during the first 3 to 6 months postoperatively and stabilization thereafter; (2) a markedly lower mean gradient at 1 year after operation (average, 6 +/- 4 mm Hg) than in stented prostheses (Intact, 22 +/- 8 mm Hg; Mosaic, 12 +/- 6 mm Hg); (3) in contrast to stented prostheses, in vivo effective orifice areas much lower (-0.91 +/- 0.35 cm(2)) than those calculated in vitro; (4) as in stented prostheses, the indexed effective orifice area (cm(2)/m(2)) is the best predictor (r = 0.77 at 1 year) of the mean gradient after operation; and (5) similar incidence of aortic regurgitation (trivial or mild, 34% versus 29% in Intact). Conclusions. The hemodynamics of the Freestyle are very satisfactory and represent a marked improvement in comparison to stented prosthesis. (C) 1998 by The Society of Thoracic Surgeons.