Duplex ultrasound for follow-up examination after stent-angioplasty of ostial renal artery stenoses

Abstract

Renal artery stenosis (RAS) may lead to deterioration of renal function and/or hypertension. Stent angioplasty has become the method of choice in the treatment of atherosclerotic ostial RAS. We describe the changes of the following duplex parameters: intrarenal resistance index RI according to Pourcelot and the renal-aortic flow velocity ratio (RAR) directly after intervention and during follow-up (FU). We also examine the value of the method in detecting restenosis. We present the results of a prospective study of 241 patients with stent angioplasty for the treatment of 355 severe RAS (extent of stenosis >/= 70 % of vessel diameter). Duplex examinations during FU were performed before discharge, after 6 and 12 months, and then annually resulting in 1292 examinations. RAR could be calculated in 98.9 % (1278/1292), RI was calculated in 100 % of the examinations. The RAR decreased significantly from 5.9 +/- 2.1 to 1.2 +/- 0.4 after intervention (p < 0.00001) with a slight increase during follow-up. RI increased significantly from 0.64 +/- 0.11 to 0.74 +/- 0.06 after intervention (p < 0.00001), equalling the RI of the contralateral side (0.74 +/- 0.07). During a mean FU of 27 +/- 15 months, 37 restenosis (10.4 %) and 12 re-restenosis were detected and confirmed angiographically, resulting in 48 reinterventions. In case of restenosis, RAR increased from 1.3 +/- 0.4 to 6.3 +/- 2.8 (p < 0.001) with a decrease to 1.3 +/- 0.6 after reintervention (p < 0.001), and RI decreased from 0.75 +/- 0.08 to 0.64 +/- 0.11 (p < 0.001) with an increase to 0.75 +/- 0.07 after reintervention (p < 0.001). Duplex ultrasound is a reliable method for FU of patients after renal artery stent-angioplasty and for detecting restenosis.