ABC of arterial and venous disease: Renal artery stenosis

Renal artery stenosis is becoming increasingly common because of atherosclerosis in an ageing population. Patients usually present with hypertension and varying degrees of renal impairment, although silent renal artery stenosis may be present in many patients with vascular disease. Despite improvements in diagnostic and interventional techniques, controversy remains over whether, when, and how to revascularise the kidneys of patients with renal artery stenosis. #### Charac teristics of renal artery stenosis ##### Fibromuscular dysplasia ##### Atherosclerosis The pathophysiology of unilateral renal artery stenosis provides a clear example of how hypertension develops. Narrowing of the renal artery, due to atherosclerosis or, rarely, fibromuscular dysplasia, leads to reduced renal perfusion. The consequent activation of the renin-angiotensin system causes hypertension (mediated by angiotensin II), hypokalaemia, and hyponatraemia (which are features of secondary hyperaldosteronism). Although these features may be reversed by correcting the stenosis, a classic presentation is uncommon, and hypertension is rarely cured in patients with atheromatous renal artery stenosis. In addition, it is now known that renal artery stenosis is underdiagnosed and may present as a spectrum of disease from secondary hypertension to end stage renal failure, reflecting variation in the underlying disease process. Thus, the presence of overt, or coincidental, renal artery stenosis usually reflects widespread vascular disease, with the associated implications for cardiovascular risk and patient survival. Atheromatous lesions may affect different sized vessels within the kidney, and multiple lesions may exist. The site limits the potential for revascularisation; only lesions within the large vessels are amenable. The commonest site, at the ostium of the renal artery, is more effectively treated by stenting. Ulcerated atheromatous plaques may also generate cholesterol microemboli (particularly after vascular intervention) #### Prevalence of atheromatous renal artery stenosis