I. Definition
A. Sometimes referred to as ischemic nephropathy; defined as narrowing of the renal arteries
B. Progressive disease in which vascular supply is interrupted and perfusion to the kidney may lead to gradual loss of renal function due to ischemia and eventual death of the organ.
C. Compensatory contralateral hypertrophy may temporarily maintain renal function.
II. Pathophysiology
A. Reduced blood flow through the renal artery causes the kidney to release increased amounts of the hormone renin.
B. Renin, a powerful blood pressure regulator, initiates a series of chemical events that result in hypertension.
C. Renal vascular hypertension can be very severe and difficult to control.
D. The kidney with renal artery stenosis (RAS) suffers from decreased blood flow and often shrinks (atrophies). This process is called “ischemic nephropathy.”
E. The other kidney is at risk for development of damage caused by hypertension.
F. Hypertensive nephrosclerosis often develops.
G. Persistently elevated blood pressures in this nonstenotic kidney may cause progressive scarring (sclerosis), leading to progressive loss of filtering function in this kidney as well.
H. Unilateral RAS and bilateral RAS can ultimately lead to chronic renal failure.
IV. Types of renal artery stenosis
A. Fibromuscular dysplasia
1. Accounts for less than 10% of RAS
2. Due to an abnormality in the muscular lining of the renal artery
3. Occurs almost exclusively in women ages 30 to 40 and rarely affects African Americans or Asians
B. Atherosclerosis
1. Leads to more than 90% of all cases of RAS
2. Most RAS is caused by atherosclerosis, or “hardening of the arteries.” Atherosclerosis is the buildup of cholesterol deposits, or plaque, in the lining of the arteries.
C. Renovascular disease
V. Clinical manifestations
A. RAS should be considered in the following circumstances:
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1. Onset of hypertension (usually sudden) at younger than age 20 or older than age 50
2. Hypertension that was well controlled has become difficult to treat.
3. Malignant, accelerated, or resistant hypertension
4. Unexplained heart failure or “flash” pulmonary edema
5. Asymmetric (differently sized and shaped) kidneys on ultrasound
a. Epigastric or renal artery bruits
b. Atherosclerotic disease of the aorta or peripheral arteries
c. Intolerance of specific antihypertensive medications—angiotensin I (ACE-I) inhibitors or angiotensin receptor blockers (ARBs)—with sudden worsening of renal function
d. Metabolic acidosis
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