Duplex sonography in the diagnosis of renovascular hypertension

Duplex sonography (DS) has become a well established method for diagnosing peripheral vascular diseases. Technical developments (higher resolution of transducer and deeper penetration) have made also abdominal and retroperitoneal vessels, including renal arteries, accessible for duplex sonography. This method provides the opportunity to recognize renal artery stenoses causing renovascular hypertension without invasive procedures. We therefore examined 86 hypertensive patients with a high likelihood of renovascular hypertension. Due to technical problems (bowel gas, adipositas) we excluded 7 patients. 79 patients (17-79 years) were included in our study. Flow patterns of several renal vascular areas were evaluated while the renal artery was demonstrated on a B-scan. A spectrum analysis included the evaluation of the frequency pattern (widening of the frequency band and loss of a frequency free window below the systolic rise?), the sloping of the diastolic shoulder, and the calculation of different parameters like acceleration index, deceleration index, resistance index, acceleration time, and systolic peak velocity. The accuracy of DS in diagnosing renal artery stenoses was compared with arterial digital subtraction angiography (DSA). Renal artery stenoses was diagnosed in 21 out of 158 renal arteries (13%). Except for the systolic peak velocity no significant correlations could be found of any of the indices from spectrum analysis with hemodynamically significant stenoses (greater than 50%). However, the following 3 criteria proved to be valuable signs of a hemodynamically significant stenoses: 1) Maximal systolic acceleration greater than 3 m/s, 2) Steep sloping diastolic shoulder, and 3) Turbulence of all frequency ranges without a frequency free window below the systolic rise. Compared with DSA the sensitivity of DS was 84.0%, the specificity was 98.5%, and the predictive value 91% in significant stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)