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

Abstract

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.

Evaluation of 17-mm St. Jude Medical Regent prosthetic aortic heart valves by rest and dobutamine stress echocardiography

“…In our study it remained substantially unchanged during stress, according to EOA and EOAi. During dobutamine infusion CO, EF, HR and double product increased significantly, confirming published data [ 4 , 9 , 12 , 13 , 15 ].…”

“…In this study we used basal and dobutamine 2-dimensional and Doppler echocardiography for assessing aortic SJMR-17 mm prostheses, implanted in patients with a small aortic root, the use of which is controversial because of the small orifice area. In our experience SJMR-17 mm prostheses showed rest mean and peak gradients of 16.6 ± 5.8 and 29.2 ± 7.1 mmHg similar to the gradients reported in literature for SJM standard or HP valves of larger sizes (19–21 mm), respectively of 17.2 ± 3.3 and 33 ± 4 mmHg [ 4 , 9 , 11 , 12 , 15 , 18 , 19 ], and slightly higher when compared to other larger (21–23 mm) bileaflet mechanical valves, respectively of 15 ± 2.6 and 27.7 ± 4 mmHg [ 4 , 5 , 9 , 12 - 15 ], although there was a large overlap between the values of these variables. When we compared EOA and EOAi of SJMR-17 mm with the reported results of larger (19–23 mm) mechanical valves, we found values slightly lower respectively 1.14 ± 0.3 cm 2 vs 1.21 ± 0.19 cm 2 and 0.76 ± 0.2 cm 2 /m 2 vs 0.88 ± 0.2 cm 2 /m 2 .…”

“…The suspected mechanisms are: increased myocardial contractility, decreased venous return to the left ventricle, mitral valve systolic anterior motion or peculiar characteristics of left ventricular geometry. This finding was detected in up to 60% of patients with a small aortic prosthesis by Hunziker et al [ 11 ], but has not been confirmed by other studies [ 4 , 9 , 12 - 14 ]. To our knowledge, this is the first report dealing with patients with 17 mm prosthetic aortic valves.…”

“…These studies clearly demonstrated a strong, inverse correlation between prosthetic size and basal and stress gradients, namely smaller valves with more elevated mean and peak gradients. Large BSA and young age have also been considered as predictors of unfavorable hemodynamics [ 5 , 11 , 12 , 17 ]. The relation between BSA and gradients is still controversial [ 5 , 11 , 12 ].…”

“…No correlation was found in our study. Young age (<50 years), especially in patients who are physically active, has been reported as predictor of potential PPM [ 11 , 12 ]. It has therefore been suggested [ 11 , 13 , 14 , 20 ] that in patients requiring a 19 mm valve or smaller, prostheses with the largest actual (nominal) orifice area (AOA) as provided by manufacturer, or other types of valve prostheses, i.e.…”