Background and aim of the study: Continuous changes are made in valve prosthesis design in order to improve hemodynamic performance. In this prospective, randomized study, hemodynamic properties of the bileaflet CarboMedics Reduced (CM-R) valve with a thinner sewing ring was compared to the Medtronic Hall (MH) disc valve. Special emphasis was placed on the ability of the two valve types to make the most effective use of the available left ventricular outflow tract (LVOT) area as defined by preoperative echocardiographic measurements.
Methods: Twenty patients scheduled for a mechanical aortic valve prosthesis were randomized to receive either a CM-R or MH valve. Only patients receiving a prosthesis £25 mm were included. A complete Doppler echocardiographic study was performed preoperatively and at six months postoperatively. Transprosthetic gradients, effective orifice area (EOA), effective orifice area index (EOAI) and LVOT- utilization

index (LVOT-UI; defined as EOA/preoperative LVOT area) were compared.
Results: The CM-R valve was superior to the MH valve for all hemodynamic parameters studied: EOA 2.03 ± 0.50 versus 1.56 ± 0.20 cm2 (p <0.01); EOAI 1.07 ± 0.22 versus 0.83 ± 0.13 cm2/m2 (p = 0.01); and LVOT-UI 0.47 ± 0.09 versus 0.38 ± 0.05 (p = 0.001). Although cardiac output was significantly higher in the CM-R group, transprosthetic gradients were lower (peak 21 ± 5 versus 27 ± 5 mmHg (p = 0.02); mean 11 ± 4 versus 13 ± 2 mmHg (p = 0.07)).
Conclusion: The results of this study showed that the CM-R aortic valve offers favorable hemodynamics compared to the MH valve. The inclusion of preoperative LVOT area measurements (as LVOT-UI) showed that the CM-R offers a more effective use of the available LVOT area.

The Journal of Heart Valve Disease 2005;14:518-522