A new accurate and non-invasive screening method for renovascular hypertension: the renal artery Doppler technique

The clinical use of ultrasonic echo Doppler velocimetry as a screening test for renal artery stenosis was investigated in 11 control subjects and 20 hypertensive patients including 10 with renovascular disease. In these hypertensive patients, the accuracy of the diagnosis of renal artery stenosis using the echo Doppler method was compared with that of angiography. The accuracy of the radionuclide renography in the same subjects was also investigated and compared with that of the echo Doppler method. Seven patients with renovascular disease who required angioplasty were examined again after the operation. The duplex Doppler signals were detected through the muscle of the back (the translumbar approach). Diagnosis of renal artery stenosis was based on three objectively defined Doppler parameters, the acceleration index, the acceleration time, and the acceleration:time ratio. In comparison with angiography, the accuracy of the echo Doppler method evaluated by using these parameters was 95%; the sensitivity was 100% and the specificity was 93%. The accuracy of the ultrasonic study was superior to that of radionuclide renography (80%). The acceleration index of the affected side was significantly correlated with the percentage stenosis of the renal artery. The changes in renal arterial blood flow following the operation were detected well by the Doppler parameters. This non-invasive method is one of the most accurate screening tests available for renovascular hypertension and has also proved quite useful for follow-up examinations in the patients with angioplasty.