Duplexsonography in the diagnosis of renovascular hypertension

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Abstract
Duplexsonography (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 duplexsonography. 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 spectrumanalysis 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 accelerationindex, decelerationindex, resistanceindex, accelerationtime, and systolic peak velocity. The accuracy of DS in diagnosing renal artery stenoses was compared with arterial digital substraction 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 spectrumanalysis with hemodynamically significant stenoses (>50%). However, the following 3 criteria proved to be valuable signs of a hemodynamically significant stenoses: 1) Maximal systolic accelaration >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. Abdominal DS seems to be a potent noninvasive method in diagnosing renal artery stenoses with a good sensitivity and a high specifity and a high predictive value.