Renal hilar Doppler analysis is of value in the management of patients with renovascular disease.

BACKGROUND: An increasing interest in the role of Doppler ultrasound and duplex scan in screening for renovascular hypertension has recently been noted. We conducted this study to define the role of renal hilar Doppler ultrasound (RHDU) in evaluating renal artery stenosis and its value in the postoperative follow-up after renal revascularization.

METHODS: One hundred and fourteen patients are included in this study with a mean age of 63.7 (11 to 89) years. Seventy-two patients underwent renal revascularization. The most frequent revascularization procedure was renal artery bypass in 82%. The RHDU results were compared with 130 angiograms done within 1 month of the RHDU study. The Doppler velocity signal in a segmental artery in the renal parenchyma was recorded, and the waveform was analyzed. An acceleration index (AI) less than 3.78 KHz/sec/MHz and an acceleration time (AT) greater than 0.1 seconds were used to indicate the presence of a significant renal artery stenosis.

RESULTS: The overall technical success rate of all RHDU studies was 93.5%. The AI value was higher in the group of patients with normal renal arteries than those with a stenosis (4.7 +/- 1.4 KHz/sec/MHz versus 1.23 +/- 1.13 kHz/sec/MHz, respectively, P <0.0001), and the AT was lower in the former group compared with the latter (0.052 +/- 0.011 sec versus 0.122 +/- 0.069 sec, P <0.0001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for AI were 89%, 92%, 85%, 94%, and 92%, respectively; and for AT were 62.5%, 97.5%, 91%, 86.5%, and 87% respectively. There was a significantly high agreement between the AI and AT results and those of arteriography (Kappa of 0.82 and 0.66, respectively, P < 0.0001). There were 10.6% kidneys with multiple renal arteries by arteriography. In these kidneys the accuracy was lower for both AI and AT and the agreement with arteriography was nonsignificant. In the postoperative period the accuracy of RHDU was 86% for AI and 95% for AT.

CONCLUSIONS: Renal hilar Doppler ultrasound has a high accuracy and agreement with arteriography in the diagnosis of renal artery stenosis. Its value is limited by the presence of multiple renal arteries, renal artery occlusion, and high incidence of postoperative false-positive results. It can be useful as a noninvasive screening test for patients suspected of having renal artery stenosis and for surveillance following renal revascularization.