Changes in glomerular filtration rate after renal revascularization correlate with microvascular hemodynamics and infilammation in swine renal artery stenosis

Background: The selection of patients with renal artery stenosis (RAS) likely to improve glomerular fltration rate (GFR) after percutaneous transluminal renal angioplasty is difficult. We examined basal hemodynamic and infilammatory factors linked to improved stenotic kidney (STK) function after percutaneous transluminal renal angioplasty in swine RAS. Methods and Results: Fifteen pigs after 6 weeks of hemodynamically significant RAS were studied before and 4 weeks after technically successful percutaneous transluminal renal angioplasty+stenting. STK and contralateral kidney hemodynamics and function were evaluated by multidetector computed-tomography before and after acetylcholine challenge. Single-kidney deoxyhemoglobin (R2^*, reciprocal to blood relaxation) and energy-dependent tubular function were assessed using blood-oxygen-level-dependent magnetic resonance imaging before and after furosemide. Baseline renal vein and inferior vena cava levels of infilammatory markers were measured and their gradient and net release calculated. Baseline parameters were compared with normal (n=7) and sham-RAS (n=7) pigs and correlated with the change in STK-GFR after revascularization (ΔGFR). Four weeks after percutaneous transluminal, renal angioplasty blood pressure was normalized in all animals, but STK-GFR improved in 10 of 15 (ΔGFR =+22.0±8.5 mL/min). ΔGFR correlated inversely with basal STK-GFR, renal release of infilammatory markers, and medullary R2 ^* response to furosemide, but directly with GFR response to acetylcholine. Basal contralateral kidney GFR correlated directly with ΔGFR. Conclusions: Low basal STK-GFR with preserved response to acetylcholine may predict benefit from revascularization in RAS, whereas renal infilammation and robust STK-R2^* responses to furosemide (possibly reflecting avid tubular oxygen consumption) are associated with less favorable outcomes. These tools may be useful for identification of patients likely to improve renal function after revascularization.