Diagnosis and quantification of aortic stenosis with pulsed doppler echocardiography

Abstract

The presence of disturbed or turbulent flow in the ascending aorta, as assessed with pulsed Doppler echocardiography, was correlated with the presence and severity of aortic stenosis in 95 patients: 18 normal subjects, 18 with a normal aortic prosthesis and 59 with clinically suspected aortic stenosis who underwent hemodynamic studies. Turbulence was defined as a frequency dispersion greater than 1.5 cm on a time interval histographic recording of the Doppler signal. Systolic turbulence was absent in all 18 normal subjects and present in the 59 patients with aortic stenosis. The patients were divided into a test group (Group I, 34 patients) and a prospective group (Group II, 25 patients). Five graphic indexes were evaluated indicative of either duration or amplitude of turbulence, amount of frequency dispersion above and below the 0 frequency shift baseline or degree of distortion of the “flow-curve” pattern of the analog signal. Chi square analysis of results in group I indicated significant (p < 0.001) differences in the magnitude of each index between patients with an aortic valve area greater than 1.0 cm 2 (n = 12) and those with an area less than 1.0 cm 2 (n = 22). When all five indexes were combined, 91 percent of patients with a valve area of less than 1.0 cm 2 had three or more indexes suggesting reduced valve area (positive score of 3 to 5), whereas 92 percent of patients with an area greater than 1.0 cm 2 had two or fewer positive indexes (p < 0.001). In Group II, 93 percent of patients with an aortic valve area of less than 1.0 cm 2 (n = 14) had a positive score of 3 to 5 whereas 82 percent of patients with an area greater than 1.0 cm 2 (n = 11) had a score of 0 to 2 (p < 0.001). The overall sensitivity of the technique (n = 59) in detecting valve areas of less than 1.0 cm 2 was 92 percent with a specificity of 87 percent; the predictive values for distinguishing areas less than from those greater than 1.0 cm 2 were 92 and 87 percent, respectively. The technique could not be used to distinguish patients with a valve area of 0.7 cm 2 or less (n = 27) from those with an area greater than 0.7 but less than 1.0 cm 2 (n = 9). Turbulence was either absent or mild (0 to 2 positive scores) in the patients with an aortic prosthesis. The presence of either aortic insufficiency (n = 17), increased age (65 years or older) (n = 20) or left ventricular dilatation or failure (n = 23) did not appear to alter the results significantly. Severity of aortic stenosis could not be assessed with M mode echocardiography in 30 of 59 patients (51 percent). Thus, pulsed Doppler echocardiography allows objective assessment of severity of aortic stenosis and may therefore be an excellent screening technique for detection of patients with an aortic valve area of less than 1.0 cm 2.