ON-X bileaflet valve in aortic position--early experience shows an improved hemodynamic profile

Despite considerable progress during the last decades, mechanical heart valves still have significant disadvantages in performance compared to native valves. To optimize the hemodynamic profile, a new mechanical bileaflet valve (ON-X) was developed and introduced in 1997. It was the aim of this study to assess the feasibility, safety, and the early postoperative hemodynamics with this new valve in vivo.

We analyzed 19 patients (11 male, 8 female; 63.2 +/- 8.2 years; aortic stenosis: n = 13; aortic incompetence: n = 2; combined aortic lesion: n = 2), undergoing aortic valve replacement with this prosthesis (valve size 19 mm: n = 1; 21 mm: n = 6; 23 mm: n = 8; 25 mm: n = 4; additional CABG: n = 4). In addition to intraoperative pressure gradient measurements, echocardiography was performed early postoperatively and after 3 months, evaluating pressure loss, effective orifice area, and regression of left-ventricular hypertrophy.

No major perioperative complications were observed. The echocardiographic evaluation demonstrated a significantly increased effective orifice area and lower transvalvular gradients in all valve sizes compared with literature values for the St. Jude Medical prosthesis. Effective regression of left-ventricular hypertrophy (-23.6%) was observed over the first three months.

These preliminary data confirm the favorable hemodynamic characteristics of the ON-X valve as compared to standard bileaflet designs. Implantation was feasible and safe, and no major postoperative complications such as thrombembolic events were observed.