Doppler Echocardiographic Assessment of the Bjork‐Shiley Monostrut Valve Prosthesis in the Aortic Position

Abstract

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 performed Doppler echocardiographic study in 106 stable patients with this prosthesis and in 7 patients with suspicion of aortic Bjork‐Shiley dysfunction. We measured maximum and mean Doppler gradients, prosthetic valvular area using the continuity equation, and degree of aortic regurgitation. The maximum and mean Doppler gradients in the 106 stable patients ranged from 9.5 to 51 mmHg (X̄= 28.9 ± 11 mmHg) and from 2 to 24 mmHg (X̄= 12.7 ± 5.2 mmHg), respectively. Maximum Doppler gradients > 45 mmHg and mean Doppler gradients > 20 mmHg occurred only in size 23 or smaller. No patient had a mean Doppler gradient > 25 mmHg. We found significant differences between sizes 25 and 27 (P < 0.01) 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 valvular area between each valve size. The correlation coefficient between the prosthetic size and the echo‐Doppler valvular area was 0.89 according to a lineal equation (SEE = 16). We could demonstrate mild aortic regurgitation in 25 cases (24%). The Doppler‐derived prosthetic valvular area was < 0.38 cm2 in two patients with obstruction and > 2 cm2 in three patients with regurgitation alone. We conclude that high pressure gradients can be observed through the smallest sizes of the Bjork‐Shiley monostrut aortic prostheses. Mild aortic regurgitation is a common finding. Our values are suggested as a reference for comparison in the case of suspected Bjork‐Shiley valve dysfunction. The Doppler‐derived prosthetic valvular area may be useful in patients with dysfunction of this prosthesis, especially to differentiate obstruction and regurgitation from regurgitation alone.