Functional Evaluation of the Bileaflet Mechanical Valve in the Aortic Position Using Dobutamine-Stress Echocardiography

The issue of valve prosthesis-patient mismatch in small annular patients is still controversial. The hemodynamic function of bileaflet mechanical valves in the aortic position was examined using dobutamine-stress echocardiography. Forty-four patients were enrolled in the study and divided into 5 groups, according to prosthesis size, from 21 mm to 29 mm. The aortic peak pressure gradient (APG) increased significantly in all groups with dobutamine-stress and exceeded 50 mmHg in 83% of the 21-mm group, in 64% of the 23-mm group, and in 33% of the 25-mm group. The APG even exceeded 80 mmHg in 22% and 18% of the 21-mm and 23-mm groups, respectively. In these cases, the potential of 'valve prosthesis-patient mismatch' was considered. From the relationship between the APG and the prosthesis valve area index (VAI), 'critical VAIs' were found where patients were likely to enter the 'mismatch' status; that is, 1.22 and 1.77 cm2/m2, respectively, for the 5 and 10 microg/kg per min stages of dobutamine stress. This critical VAI range is useful in predicting the 'mismatch' patients preoperatively. Alternative procedures or prostheses should then be selected for them.