[Limitation of Doppler echocardiography in evaluation of aortic valve prostheses]]

Doppler echocardiography has been widely used as a noninvasive method to evaluate valvular heart diseases. However, the diagnostic impact of Doppler echocardiography in the evaluation of prosthetic valves is discussed controversially. Reasons are, on one hand, the high variabilities of transvalvular gradients observed for normal prosthetic devices and, on the other hand, results of experimental in vitro studies demonstrating an impressive discrepancy between Doppler-echocardiographic and invasive measurements of the transvalvular gradients in prosthetic valves. In a prospective study, we evaluated 11 out of 335 patients after aortic valve replacement who demonstrated an elevated transvalvular gradient over the prosthetic valve. Eight patients had a St. Jude medical prosthesis (19-23 mm), two patients had a Medtronic Hall prosthesis, and one patient a Björk-Shiley prosthesis. The maximal instantaneous gradient measured by Doppler-echocardiography was 74 +/- 15 mmHg, the mean gradient was 47 +/- 12 mmHg. The prosthetic orifice area calculated by the continuity equation using the left ventricular outflow tract diameter was 0.86 +/- 0.25 cm2, and that calculated by using the prosthetic ring diameter was 0.98 +/- 0.23 cm2. None of the patients had a severe aortic valve regurgitation. All patients were clinically asymptomatic. Transesophageal echocardiography and x-ray showed a normal prosthetic function. Angiographic examination performed in seven patients showed a peak-to-peak gradient of 26 +/- 9 mmHg, and demonstrated a marked discrepancy between Doppler-echocardiographic and invasive results. These results confirm the clinical limitations of Doppler echocardiography to distinguish between normal and disturbed prosthetic function.(ABSTRACT TRUNCATED AT 250 WORDS)