[Echodoppler evaluation of the normally functioning Saint-Jude's aortic valve prosthesis]

The aims of this study were: to define Doppler echocardiographic criteria of normality of aortic St Jude Medical (SJM) valve prostheses with respect to their size and to verify the validity of the continuity equation in the determination of prosthetic valve functional surface area. Forty patients with apparently normally functioning SJM prostheses without other cardiac disease were investigated at least one month after surgery. The group consisted in 1 n. 19, 6 n. 21, 9 n. 23, 12 n. 25 and 12 n. 27 SJM prostheses. The following parameters were measured: the maximum transprosthetic velocity, maximum and mean transprosthetic pressure gradients, permeability index and the Doppler surface area calculated by the continuity equation using the method proposed by Skjaerpe. The global results were as follows: maximum velocity = 2.5 +/- 0.4 m/s (1.8-3.7 m/s); maximum gradient = 26.9 +/- 9.8 mmHg (14-53 mmHg); mean gradient = 13.7 +/- 5.6 mmHg (7-30 mmHg); permeability index = 0.41 +/- 0.09 (0.23-0.57); Doppler surface area = 1.89 +/- 0.66 cm2 (0.73-3.23 cm2). When the prostheses were considered according to their sizes a weak negative correlation was observed between the mean pressure gradients and the size of the prostheses: r = -0.43, p less than 0.05 and a positive correlation between Doppler surface area and the theoretical prosthetic surface area: r = 0.71, p less than 0.005; SD = 0.45 cm2. No significant differences were observed between the pressure gradients and velocities of each size of prosthesis except when sizes 21 + 23 were compared with the large sizes (n. 25 + 27).(ABSTRACT TRUNCATED AT 250 WORDS)