DOPPLER-ECHOCARDIOGRAPHIC ASSESSMENT OF THE BJORK-SHILEY MONOSTRUT VALVE PROSTHESIS IN THE AORTIC POSITION

In order to determine the standard Doppler hemodynamic characteristics of the Bjork-Shiley monostrut aortic prosthesis and the value of the continuity equation to calculate the prosthetic valvular area, we perf ormed Doppler echocardiographic study in 106 stable patients with this prosthesis and in 7 patients with suspicion of aortic Bjork -Shiley d ysfunction. We measured maximum and mean Doppler gradients, prosthetic valvular area using the continuity equation, and degree of aortic reg urgitation. The maximum and mean Doppler gradients in the 106 stable p atients ranged from 9.5 to 51 mmHg (XBAR = 28.9 +/- 11 mmHg) and from 2 to 24 mmHg (XBAR = 12.7 +/- 5.2 mmHg), respectively. Maximum Doppler gradients > 45 mmHg and mean Doppler gradients > 20 mmHg occurred onl y in size 23 or smaller. No patient had a mean Doppler gradient > 25 m mHg. We found significant differences between sizes 25 and 27 (P < 0.0 1) and 21 and 25 (P < 0.01), but not between sizes 19, 21, and 23, or 23 and 25. There was significant difference in Doppler prosthetic valv ular area between each valve size. The correlation coefficient between the prosthetic size and the echo-Doppler valvular area was 0.89 accor ding to a lineal equation (SEE = 16). We could demonstrate mild aortic regurgitation in 25 cases (24%). The Doppler-derived prosthetic valvu lar area was < 0.38 cm2 in two patients with obstruction and > 2 cm2 i n three patients with regurgitation alone. We conclude that high press ure gradients can be observed through the smallest sizes of the Bjork- Shiley monostrut aortic prostheses. Mild aortic regurgitation is a com mon finding. Our values are suggested as a reference for comparison in the case of suspected Bjork-Shiley valve dysfunction. The Doppler-der ived prosthetic valvular area may be useful in patients with dysfuncti on of this prosthesis, especially to differentiate obstruction and reg urgitation from regurgitation alone.