In a patient with an abdominal bruit, refractory hypertension, and vascular risk factors, consider renal artery stenosis. The best initial step in management is renal ultrasound with Doppler.
In renal artery stenosis, there is decreased blood flow to the juxtaglomerular apparatus causing activation of the renin-angiotensin-aldosterone system and hypertension. Renal artery stenosis is the most common cause of secondary hypertension. Underlying causes include atherosclerosis (more common in elderly men) and fibromuscular dysplasia (usually seen in young females). Disease may be unilateral or bilateral. Suspect renal artery stenosis in a patient with hypertension but no family history and blood pressure which is resistant to medical therapy. The best initial step in management is a renal ultrasound with Doppler. Confirmation can be done with magnetic resonance angiography, duplex ultrasonogram, a nuclear renogram or a renal angiogram (most accurate). Possible treatments include revascularization with percutaneous transluminal renal angioplasty, bypass surgery, or conservative medical therapy with calcium blockers and statins. ACE inhibitors should NOT be used in patients with bilateral renal artery stenosis as they may precipitate acute renal failure.
Viera and Neutze discuss the diagnosis of secondary hypertension. A secondary etiology may be suggested by flushing and sweating (suggestive of pheochromocytoma), a renal bruit (suggestive of renal artery stenosis), or laboratory abnormalities such as hypokalemia (found in hyperaldosteronism). Secondary hypertension should also be considered in patients with resistant hypertension and early or late onset of hypertension.
O'Neill et al. discuss imaging for renovascular disease. Ultrasonography, computed tomography angiography, and magnetic resonance angiography, as well as conventional angiography, each have advantages and disadvantages. There is no clear data supporting one modality or clear consensus. Often, the decision is made based on the level of expertise that is available.
Illustration A depicts a 3-D MRI reconstruction classic for unilateral renal artery stenosis.
Answer 1: Reassurance is inappropriate as his blood pressure is dangerously high and does not represent a normal increase in blood pressure seen with aging.
Answer 2: This is a very common answer choice because it certainly is the most accurate test for renal artery stenosis however the question asked for the best initial step in management. It would be more reasonable for Step 1/2/3 to begin with a simple and noninvasive assessment with renal ultrasound with doppler.
Answer 4: Revascularization has a higher success rate in fibromuscular dysplasia in comparison to renal artery stenosis secondary to atherosclerosis. It would be premature to begin treatment without an initial diagnostic test.
Answer 5: ACE inhibitors are contraindicated in patients with bilateral disease since they may precipitate acute renal failure. They would only be used if all other attempts in management failed and you were only trying to maintain blood pressure.
Viera AJ, Neutze DM.Diagnosis of secondary hypertension: an age-based approach.Am Fam Physician. 2010 Dec 15;82(12):1471-8.
PMID:21166367 (Link to Abstract)
O'Neill WC, Bardelli M, Yevzlin AS.Imaging for renovascular disease.Semin Nephrol. 2011 May;31(3):272-82. doi: 10.1016/j.semnephrol.2011.05.007.
PMID:21784276 (Link to Abstract)