[Doppler echocardiographic evaluation of aortic valve prosthesis. Analysis of the reproducibility of pressure gradients and surface measurements].

Doppler echocardiography has become the method of choice for the evaluation of cardiac valve prostheses. In order to determine the reproducibility of the measurements of pressure gradient and valve surface area, 55 patients with aortic valve prostheses without clinical dysfunction and having at most a trivial regurgitation on color Doppler examination underwent a double evaluation during an average interval of 9 +/- 5 months. The maximum and mean pressure gradients were recorded and the valve surface area calculated using the continuity equation in all cases. The subaortic diameter was taken to be constant and equal to the external diameter of the prosthesis. No significant differences were found between the two evaluations of mean pressure gradient and valve surface area. The intra-patient variability was +/- 8 mmHg for the maximum pressure gradient, +/- 6 mmHg for the mean pressure gradient, +/- 0.33 cm2 for valve surface area calculated using the maximum velocities and +/- 0.44 cm2 when the velocity-time integrals were used. When expressed as a percentage, the mean coefficient of variation was 21 +/- 17% for the maximum pressure gradient, 21 +/- 18% for the mean pressure gradients, 21 +/- 15% for the valve surface area calculated using the maximum velocities and 22 +/- 14% when the ratio of velocity-time integrals was used.(ABSTRACT TRUNCATED AT 250 WORDS)