Hemodynamic Index of Atheromatous Renal Artery Stenosis for Angioplasty

Abstract

Background and objectives: Trans-stenotic pressure gradient across the constriction (PG), a hemodynamic variable of atheromatous renal artery stenosis (ARAS), is a widely used indicator for angioplasty, but its association with the outcome of angioplasty has not been fully investigated.Design, setting, participants & measurements: In 34 hypertensive cases with unilateral ARAS, we evaluated hemodymanic variables of ARAS with reference to the systemic BP reduction after angioplasty as the outcome.Results: In each phase, PG divided by its corresponding prestenotic arterial BP (PG/preBP) had better association with the outcome than PG. The mean phase PG/preBP had the largest area under the curve in the receiver operating characteristic analysis (0.794) with the sensitivity/specificity of 0.957/0.545 for its cut-off >0.15. Although the plasma renin activity, which reflects the perfusion to renal parenchyma, was higher in the angioplasty-efficacious cases than in the angioplasty-inefficacious cases before angioplasty (7.8 ؎ 6.6 versus 3.4 ؎ 3.8 ng/ml/h, P ‫؍‬ 0.049), it was not generally reduced by angioplasty independent of the outcome.Conclusions: As the index to select ARAS for angioplasty, PG/preBP was better than PG and the mean phase PG/preBP could be the best. However, other factors such as the microvascular kidney disease, which affect the perfusion to renal parenchyma, would influence the outcome.

Stage of chronic kidney disease is an outcome-predicting factor of angioplasty for atheromatous renal artery stenosis

“…8 For the case with the total score reduction, it was confirmed that neither the office BP nor the self-monitored BP increased after PTRA-S treatment.…”

“…Given that PTRA-S equally reduced PG at ARAS lesion sites in both groups, perfusion recovery at these sites would not have affected the increase in DTPA-GFR. 7,8,15,23 In addition, because the RIs (an index for vascular resistance) of interlobar arteries were not different between the groups, 1,2,24 perfusion impairment in these arteries also would not have affected the increase in DTPA-GFR. The perfusion impairment in more distal arteries may have affected the increase.…”

“…25 The present finding that cases at CKD stages 1-3 did not have long-term reno-preservation despite the low intrarenal RI (o0.80) supports the findings of Zeller et al 25 The parenchymal perfusion would have been preserved before PTRA-S treatment in the DTPA-GFR-nonincreased group, in which most cases were at CKD stages 1-2. 16,17 Given that ARAS had impaired the perfusion before PTRA-S treatment in both groups, 7,8,15,23 some supplementary pathways for blood supply such as the collateral arteries would have preserved the perfusion in the group. In contrast, in the DTPA-GFR-increased group, supplementary blood supply might not have been sufficient for the preservation, and PTRA-S treatment could have improved the perfusion.…”

“…8,15 The pressure levels measured distal and proximal to the lesion were recorded as the post-stenotic and the pre-stenotic pressure, respectively. PG was calculated as the post-stenotic pressure subtracted from its corresponding pre-stenotic pressure.…”

“…8 We showed that the cases could be selected on the basis of the value of the trans-stenotic pressure gradient (PG) at ARAS divided by its corresponding pre-stenotic pressure (PG/pre). However, we were unable to define the cases that would have renal function improvement after PTRA-S treatment because of the difficulty in evaluating the improvement.…”