Invasive treatment of renal artery stenosis - effects on blood pressure, medication, renal function and inflammatory biomarkers

University dissertation from Lund University, Faculty of Medicine

Abstract: Renal artery stenosis (RAS) causes hypertension, decreased glomerular filteration rate (GFR), and renal ischemia. RAS is progressive and causes 5-16% of all cases of renal failure. Prevalence of RAS in patients with hypertension is 1-5%. Today percutaneous transluminal renal angioplasty (PTRA) with or without stenting is a widely accepted treatment of RAS. Treatment of renal artery occlusion (RAO) by PTRA and inflammatory biomarkers in RAS has not previously been well studied. The aims of this thesis were to evaluate the outcome of PTRA and open surgical revascularisation for RAS, to evaluate PTRA with or without stenting in RAO and PTRA in RAS caused by fibromuscular dysplasia (FMD), to evaluate whether mean pressure gradient (MPG) over RAS before and after PTRA predicts the outcome, and to evaluate whether inflammatory biomarkers and endothelin (ET) are increased in patients with RAS, and how treatment with PTRA affects these variables during the first month after intervention. Results: Blood pressure (BP) decreased by revascularisation in RAS, with better long-time survival after PTRA compared to surgery, but with shorter time to re-do (7 months vs. 15 months). In RAO, absence of nephrosclerosis, and a shorter duration of hypertension predicted favourable clinical outcome. After PTRA in patients with FMD, cure was obtained in 24% of the patients. FMD involving branch arteries and longer hypertension duration before PTRA predicted less favourable effect on systolic BP (SBP). MPG correlated with SBP before PTRA and during follow-up. Residual MPG after PTRA predicted endovascular re-do (52% versus 14%). Levels of inflammatory biomarkers and ET-1 were higher in RAS patients than in healthy control subjects. One month after PTRA, SBP, interlukin-6 (IL-6) and ET-1 were lower than before intervention, whereas CD40 ligand had increased compared to baseline. Conclusion: PTRA was as effective as open revascularisation, with lower complication rate and lower early and long-time mortality, but with shorter time to first re-do. RAO can be treated with endovascular techniques. Revascularisation has beneficial long-term effects in FMD. PTRA has positive effects on BP and antihypertensive medication in RAS with MPG ?10 mmHg. Residual MPG post PTRA predicts restenosis but not the outcome of the intervention. In patients with RAS, PTRA triggers rapid transient increases in hs-CRP and IL-6. However, one month after PTRA, both IL-6 and ET-1 had decreased compared to before intervention indicating beneficial effects of PTRA on inflammation and the ET system.

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