Renovascular disease

1. What clinical syndromes are associated with renal artery stenosis?

Renovascular hypertension, progressive loss of kidney function from ischemic nephropathy, and recurrent episodes of flash pulmonary edema (meaning acute/abrupt onset pulmonary edema) are the clinical syndromes typically associated with renal artery stenosis. However, renal artery stenosis can also be completely asymptomatic. In the case of renovascular hypertension, hemodynamically significant unilateral orbilateral renal artery stenosis leads to decreased perfusion pressure in one or both kidneys. This stimulates activation of the renin-angiotensin-aldosterone system, which increases systemic pressure to restore kidney perfusion distal to the stenotic lesion(s).

The pathophysiology of ischemic nephropathy is complex and likely relates to activation of multiple pathways triggered by reduced kidney perfusion that promote kidney injury and fibrosis. Flash pulmonary edema in the context of renal artery stenosis tends to occur only with bilateral stenosis (or renal artery stenosis affecting a solitary kidney). In this situation, patients are likely predisposed to episodes of pulmonary edema from enhanced tubular sodium reabsorption and volume expansion from increased renin-angiotensin-aldosterone activity in the absence of a pressure natriuresis phenomenon that would occur within an unaffected kidney.

2. What are the two main causes of renal artery stenosis?

The two important causes of renal artery stenosis are atherosclerosis and fibromuscular dysplasia. Atherosclerotic renal artery stenosis is the more common cause and is often seen in older patients. It occurs in the setting of atherosclerotic disease affecting other vascular beds, such as the coronary, cerebral, and peripheral arterial circulation. These patients often have other risk factors for atherosclerosis, such as diabetes, hypertension, and smoking. In contrast, fibromuscular dysplasia is typically seen in younger female patients.

3. How common is renal artery stenosis?

It depends on the population examined. Some degree of renal artery stenosis will be found incidentally in 19% to 42% of patients with atherosclerotic vascular disease such as coronary artery disease or peripheral vascular disease. Fibromuscular dysplasia causing renal artery stenosis is seen in 3% to 5% of healthy patients being evaluated as potential living kidney donors. In studies examining patients with mild to moderate hypertension, renal artery stenosis has been found in 0.6% to 3% of this population. In patients with refractory hypertension, renal artery stenosis may be found in between 10% and 45% of patients.

4. How often does renal artery stenosis lead to end-stage kidney disease?

In some series of patients receiving dialysis, atherosclerotic renal artery stenosis may lead to end-stage kidney disease in up to 15% of patients. However, in the most recent United States Renal Data Service report, which is a registry that tracks various data on virtually all patients receiving dialysis in the United States, the incidence of renal artery stenosis as the cause for end-stage kidney disease was only 0.6%.

5. Who is at risk of developing renal artery stenosis?

Patients with risk factors for atherosclerotic vascular disease, such as hypertension, dyslipidemia, diabetes, tobacco use, and older age, are at increased risk for atherosclerosis affecting the renal arteries causing stenosis.