Renovascular hypertension: diagnostic and therapeutic challenges

Abstract

Atherosclerotic renal artery stenosis (ARAS) is associated with two common clinical syndromes: renovascular hypertension and ischemic nephropathy, which often coexist. The ensuing renovascular disease constitutes the fastest-growing etiology of end-stage renal disease. Diagnostic work-up for hemodynamical significant renal artery stenosis should be restricted to patients suspected to be at moderate or high risk for renovascular disease. Patients at moderate risk should first undergo a screening test, like Doppler ultrasonography or captopril-enhanced scintigraphy. In case of a positive screening test, renal artery imaging with either spiral computed tomography angiography or magnetic resonance angiography with Gadolinium is indicated. Patients at high risk for renovascular disease may be directly referred for intra-arterial renal artery angiography, the golden standard diagnostic procedure. A renal artery stenosis with narrowing of > 50-60% of the lumen, is considered hemodynamically significant, and may be suitable for treatment with angioplasty or angioplasty plus stent placement (in case of osteal renal artery stenosis). The therapeutic approach of the hypertensive patient with a hemodynamically significant renal artery stenosis is currently a matter of great debate. In any case optimal medical therapy with antihypertensive, lipid-lowering, and platelet-inhibiting drugs should be instituted, since such approach may not only prevent the progression to end-stage renal disease, but may also prevent the progression of extra-renal vascular disease, which affects the majority of these patients. Current evidence suggests that angioplasty (with additional stent placement in case of osteal renal artery stenosis) may benefit a subset of patients with significant RAS, i.e. patients with a resistance index < 80% at the level of the segmental renal arteries, and patients with bilateral RAS or patients with unilateral RAS with a unique functioning kidney. Prospective, randomized and controlled studies with clearly defined clinical endpoints are needed to better define the absolute and relative indications of angioplasty (plus stenting) in the setting of renal artery stenosis.