Comparative rest and exercise hemodynamics of 23-mm stentless versus 23-mm stented aortic bioprostheses

Background. The hemodynamic superiority of stentless valves at rest has been generally accepted, but there is a lack of studies on exercise hemodynamics. Methods. We assessed aortic valve hemodynamics at rest and during exercise in 10 patients with a 23-mm stentless aortic bioprosthesis (Medtronic Freestyle; Medtronic Europe SA/NV, St. Stevens Woluwe, Belgium), in 10 patients with a 23-mm stented aortic bioprosthesis (Carpentier-Edwards, SAV, model 2650; Baxter Edwards AG, Horw, Switzerland), and in 10 healthy volunteers (control group) by means of Doppler echocardiography. Results. Gradients at rest and gradients on comparable maximum exercise levels were significantly lower in patients with stentless valves compared to those with stented valves (rest: 6 ± 2/11 ± 4 mm Hg [mean/peak] versus 12 ± 3/21 ± 10 mm Hg; exercise: 9 ± 3/18 ± 6 mm Hg [mean/peak] versus 22 ± 8/40 ± 11 mm Hg). Patients with stentless valves revealed, in comparison to healthy young men, significantly higher gradients, but the small gradient difference of 3/7 mm Hg (mean/peak) at rest remained nearly unchanged throughout the exercise protocol (4/8 mm Hg [mean/peak] at 25 W, 4/9 mm Hg at 50 W and 4/9 mm Hg at 75 W). In contrast, the gradient difference between patients with stented and stentless valves increased significantly from one exercise level to the next (6/12 mm Hg [mean/peak] at rest, 8/14 mm Hg at 25 W, 12/17 mm Hg at 50 W, and 15/25 mm Hg at 75 W). Conclusions. A stentless aortic bioprosthesis seems to be an appropriate aortic valve substitute, especially in patients who perform regular physical exercise.