Renal artery stenosis is a common cause of secondary hypertension and it can present in 0.5-5% of all hypertensive patients. In patients with systemic atherosclerosis the prevalence can be even higher, around 20-30%.
There are two major causes of renal artery stenosis:
Atherosclerosis (90% of cases)
Fibromuscular dysplasia (10% of the cases)
SIGNS & SYMPTOMS:
It can be a silent condition for a long period. Signs and symptoms, when present, may include:
Unexplained and often refractory hypertension
Signs and symptoms associated with atherosclerosis (e.g. angina, abdominal pain, claudication) or fibromuscular dysplasia.
Decline in kidney function, particularly after starting ACE inhibitors (>30% eGFR decline after starting the medication).
Patients with hypertension that is hard to control (need for multiple drugs), patients with progressive kidney failure, young patients with suspected fibromuscular dysplasia or patients with flash pulmonary edema should be tested for renal artery stenosis.
Initial testing can be done with Doppler ultrasonography (peak systolic velocity above 200cm/sec indicates possible stenosis >60%), CT angiography or MR angiography (stenosis >75% or >50% with poststenotic dilation suggests renovascular hypertension).
Other tests that may be used include captopril renogram (may be useful to see which kidney is working better), plasma renin activity and renal vein sampling (renin secretion is higher on the kidney with stenosis).
Since renal artery stenosis can be caused by atherosclerosis, patients may receive general treatment to reduce the cardiovascular risk (secondary prevention), such as lifestyle modifications, aspirin, statins, beta-blockers and ACE inhibitors (caution with the latter since, although effective, they may increase the risk of chronic kidney disease in this patients).
Most patients will have unilateral disease. Medical therapy may be enough for unilateral disease, except in patients that cannot tolerate it or in those with recurrent pulmonary edema. If intervention is required percutaneous transluminal renal angioplasty with stent placing is the method of choice. Open surgery is only considered if the anatomy is not favorable or if angioplasty fails.
Bilateral stenosis (or unilateral stenosis a unilateral functional kidney) should be treated with medication initially. Patients that do not respond to medication (e.g. maintain hypertension, lose kidney function, have recurrent flash pulmonary edema) should receive revascularization, ideally with angioplasty and stenting (surgery only if the endovascular therapy fails).
SOUCES & FURTHER READING:
- Dworkin LD, Cooper CJ. Renal-Artery Stenosis. N Engl J Med. 2009 Nov 12; 361(20): 1972–1978.
- Bax L et al. Stent Placement in Patients With Atherosclerotic Renal Artery Stenosis and Impaired Renal Function: A Randomized Trial. Ann Intern Med. 2009;150(12):840-848.
- Wheatley K et al. Revascularization versus Medical Therapy for Renal-Artery Stenosis. N Engl J Med 2009; 361:1953-1962.
- Safian RD, Textor SC. RENAL-ARTERY STENOSIS. N Engl J Med, Vol. 344, No. 6 · February 8, 2001.
- Cooper CJ et al. Stenting and Medical Therapy for Atherosclerotic Renal-Artery Stenosis. N Engl J Med 2014; 370:13-22.