MESURE DES GRADIENTS TRANSVALVULAIRES PAR LE DOPPLER. ENREGISTREMENTS SIMULTANES DOPPLER-CATHETERISME CHEZ 78 PATIENTS

Several studies have demonstrated the value of Doppler ultrasound as a means of measuring gradients across cardiac valves. However, in view of sudden variations in cardiac output gradients should be measured simultaneously by Doppler and catheterization in order to validate the former method and determine its accuracy. We conducted a prospective study with simultaneous recordings in 78 patients with aortic valve stenosis (33) or mitral valve stenosis (19) or cardiac valve prosthesis (26). Mean age of the patients was 55 ± 14 years, and 50% of them were male. Subjects with pure or predominant regurgitation were excluded from the study. In the whole of the population studied, correlation between Doppler ultrasound and haemodynamics was very good with r = 0.98, p < 0.001 for maximum gradient and r = 0.96, p < 0.001 for mean gradient. The perfect simultaneity of the haemodynamic and ultrasonic recordings was confirmed by comparing the duration of gradients measured by the two methods (r = 0.996, p < 0.001). There also was very close correlation between ultrasounds and catheter in patients with mitral stenosis (maximum gradient r = 0.98, p < 0.001; mean gradient r = 0.97, p < 0.001). Mean Doppler-catheter differences were not significant, and no underestimation by Doppler reached or exceeded 5 mmHg. Correlations were also satisfactory in patients with aortic stenosis (maximum gradient r = 0.97, p < 0.01; mean gradient r = 0.90, p < 0.001). By using a simplified method in which the Doppler curve area is assimilated to a hemi-ellipse, planimetry for calculation of the mean gradient could be avoided and good results were obtained (r = 0.94, p < 0.001). Mean Doppler-catheter differences were small but significant; underestimations by Doppler were always moderate. In clinical practice the Doppler ultrasound is much superior to echography and phonomechanography for the diagnosis of tight aortic stenosis. In patients with cardiac valve prosthesis correlations remained good (maximum gradient r = 0.91, p < 0.01; mean gradient r = 0.84, p < 0.001), but the relative error of measurement was high and the differences were significant. It is concluded that Doppler ultrasound is a highly reliable, noninvasive method for measuring gradients across cardiac valves and that its results are closely correlated with haemodynamic values. Its contribution to clinical practice is determinant, especially for native valves.