Angioplasty of atherosclerotic and fibromuscular renal artery stenosis: time course and predicting factors of the effects on renal function

Abstract

The effects of percutaneous transluminal renal angioplasty (PTRA) on the renal function of stenotic kidneys are usually assessed by evaluating the changes in serum creatinine, which is quite a rough indicator of glomerular filtration rate (GFR). In 27 hypertensive patients with 19 atherosclerotic and 11 fibromuscular significant renal artery stenoses, we investigated with renal scintigraphy the short-term (5 days) and long-term (10 months) effects of a technically successful PTRA (in seven cases combined with a stent implantation) on GFR of the stenotic and contralateral kidneys; these measurements were combined with those of plasma renin activity (PRA) and of angiotensin II (AII). We found that in short-term studies after PTRA GFR rose from 29.7 ± 3.5 to 34.6 ± 3.1 mL/min and from 36.9 ± 4.0 to 45.1 ± 4.3 mL/min, respectively, in atherosclerotic and fibromuscular poststenotic kidneys. In long-term studies GFR further and significantly increased, to 37.8 ± 3.2 mL/min in the former group, whereas it stabilized in the latter group (46.0 ± 3.6 mL/min). In patients with fibromuscular stenosis these changes in GFR were associated with clear-cut reductions in blood pressure (BP), PRA, and AII; these decrements also occurred in patients with atherosclerotic stenosis but to a much lesser extent. We also found that in short- and long-term studies the percent of PTRA-induced increments of GFR in the poststenotic kidneys were inversely correlated with the baseline values of GFR. In addition, the absolute and percent increments of GFR were positively correlated with the basal levels of AII. Thus the time course of the improvement in GFR after angioplasty may differ in kidneys, depending on the etiology of the stenosis, in that in those with fibromuscular stenosis it was entirely apparent within a few days whereas in those with atherosclerotic stenosis it required several months to be fully expressed. Also, it appears that the more compromised kidneys are those that benefit most from the dilatation and that AII levels are useful indicators of the possibility that the stenotic kidney will have a favorable functional outcome in terms of restoration of renal blood flow.