renal artery stenosis

Renal Artery Stenosis 

Definition

Renal artery stenosis is a blockage or narrowing of the major arteries that supply blood to the kidneys.

Description

Renal artery stenosis occurs when the flow of blood from the arteries leading to the kidneys is constricted by tissue or artherosclerotic plaque. This narrowing of the arteries diminishes the blood supply to the kidneys, which can cause them to atrophy and may ultimately lead to kidney failure. It may also cause renovascular hypertension, or high blood pressure related to renal artery blockage.

Causes and symptoms

The two main causes of renal artery stenosis are atherosclerosis and fibromuscular disease. Fibromuscular diseases such as fibromuscular dysplasia cause growth of fibrous tissues on the arterial wall. Stenosis may also occur when scar tissue forms in the renal artery after trauma to the kidney.

Renal arterial stenosis has no overt symptoms. Eventually, untreated renal arterial stenosis causes secondary complications such as chronic kidney failure, which may be characterized by frequent urination, anemia, edema, headaches, hypertension, lower back pain, and other signs and symptoms.

Diagnosis

The high blood pressure that is sometimes associated with renal artery stenosis may be the first sign that it is present, particularly if the hypertension is not responding to standard treatment. Presence of a bruit, a swooshing sound from the artery that indicates an obstruction, may be heard through a stethoscope.

An arteriogram, an x-ray study of the arteries that uses a radiopaque substance, or dye, to make the arteries visible under x ray, may also be performed. This test is used with caution in patients with impaired kidney function, as the contrast medium may cause further kidney damage.

Treatment

Treatment for renal artery stenosis is either surgical, pharmaceutical, or with angioplasty or stenting. Angioplasty involves guiding a balloon catheter down into the renal artery and inflating the balloon to clear the blockage. A stent may be inserted into the artery to widen the opening. Some patients may be candidates for surgical revascularization, which involves restoring blood flow with an arterial bypass. Drugs known as angiotension-converting enzyme (ACE) inhibitors may be prescribed for some patients. The chosen treatment approach depends on the cause of the stenosis and factors such as the patient's kidney function and blood pressure control.

Alternative treatment

Renal artery stenosis is a serious and potentially life-threatening condition, and should always be treated by a healthcare professional familiar with the disorder.

Prognosis

Untreated renal artery stenosis can cause hypertension (high blood pressure) and may ultimately lead to chronic kidney failure (end-stage renal disease).

Prevention

Maintaining a heart healthy lifestyle can help to prevent cases of renal arterial stenosis attributable to artherosclerosis. Strategies for avoiding vascular disease include eating right, maintaining a desirable weight, quitting smoking, managing stress, and exercising regularly.

Resources

Periodicals

Bloch, M. J., and T. Pickering. "Renal Vascular Disease: Medical Management, Angioplasty, and Stenting." Seminars in Nephrology 20, no. 5 (September 2000): 474-88.

Fenves, A. Z., and C. V. Ram. "Fibromuscular Dysplasia of the Renal Arteries." Current Hypertension Reports 1, no. 6 (December 1999): 546-9.

Organizations

American Kidney Fund (AKF). Suite 1010, 6110 Executive Boulevard, Rockville, MD 20852. (800)638-8299. 〈http://www.arbon.com/kidney/〉.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Natcher Building, 6AS-13K, 45 Center Drive, Bethesda, MD 20892-6600. http://www.niddk.nih.gov.

National Kidney Foundation. 30 East 33rd Street, New York, NY 10016. (800)622-9020. http://www.kidney.org.

Key terms

Artherosclerotic plaque — A deposit of fatty and calcium substances that accumulate in the lining of the artery wall, restricting blood flow.

Atrophy — Cell or tissue wasting or death.

Chronic kidney failure — End-stage renal disease (ESRD); chronic kidney failure is diagnosed as ESRD when kidney function falls to 5-10% of capacity.

Edema — Swelling which occurs when body tissues retain fluid.

Stent — An expandable "scaffold-like" device, usually constructed of a stainless steel material, that is inserted into an artery to expand the inside passage and improve blood flow.

---

stenosis /ste·no·sis/ (stĕ-no´sis) pl. steno´ses   [Gr.] stricture; an abnormal narrowing or contraction of a duct or canal.

---

aortic stenosis  (AS) a narrowing of the aortic orifice of the heart or of the aorta near the valve.

hypertrophic pyloric stenosis  narrowing of the pyloric canal due to muscular hypertrophy and mucosal edema, usually in infants.

hypertrophic subaortic stenosis , idiopathic hypertrophic subaortic stenosis (IHSS) a form of hypertrophic cardiomyopathy in which the left ventricle is hypertrophied and the cavity is small; it is marked by obstruction to left ventricular outflow.

infantile hypertrophic gastric stenosis  congenital hypertrophy and hyperplasia of the musculature of the pyloric sphincter, leading to partial obstruction of the gastric outlet.

mitral stenosis  a narrowing of the left atrioventricular orifice.

pulmonary stenosis  (PS) narrowing of the opening between the pulmonary artery and the right ventricle, usually at the level of the valve leaflets.

pyloric stenosis  obstruction of the pyloric orifice of the stomach; it may be congenital or acquired.

renal artery stenosis  narrowing of one or both renal arteries, so that renal function is impaired, resulting in renal hypertension and, if stenosis is bilateral, chronic renal failure.

subaortic stenosis  aortic stenosis due to an obstructive lesion in the left ventricle below the aortic valve, causing a pressure gradient across the obstruction within the ventricle.

tricuspid stenosis  (TS) narrowing or stricture of the tricuspid orifice of the heart.

---

stenosis [stĕ-no´sis] (pl. steno´ses)

an abnormal narrowing or contraction of a body passage or opening; called also arctation, coarctation, and stricture.

aortic stenosis obstruction to the outflow of blood from the left ventricle into the aorta; in the majority of adult cases the etiology is degenerative calcific disease of the valve.

hypertrophic subaortic stenosis (idiopathic hypertrophic subaortic stenosis) a cardiomyopathy of unknown cause, in which the left ventricle is hypertrophied and the cavity is small; it is marked by obstruction to left ventricular outflow.

mitral stenosis a narrowing of the left atrioventricular orifice (mitral valve) due to inflammation and scarring; the cause is almost always rheumatic heart disease. Normally the leaflets open with each pulsation of the heart, allowing blood to flow from the left atrium into the left ventricle, and close as the ventricle fills again so that they prevent a backward flow of blood. In mitral stenosis there is a resultant increase of pressure in the pulmonary artery and hypertrophy of the left ventricle. The usual treatment is surgical replacement of the valve.

pulmonary stenosis (PS) narrowing of the opening between the pulmonary artery and the right ventricle.

pyloric stenosis see pyloric stenosis.

renal artery stenosis narrowing of one or both renal arteries by atherosclerosis or by fibrous dysplasia or hyperplasia, so that renal function is impaired (see ischemic nephropathy). Increased renin release by the affected kidney causes renovascular hypertension, and bilateral stenosis may result in chronic renal failure.

spinal stenosis narrowing of the vertebral canal, nerve root canals, or intervertebral foramina of the lumbar spine, caused by encroachment of bone upon the space; symptoms are caused by compression of the cauda equina and include pain, paresthesias, and neurogenic claudication. The condition may be either congenital or due to spinal degeneration.

subaortic stenosis aortic stenosis due to an obstructive lesion in the left ventricle below the aortic valve, causing a pressure gradient across the obstruction within the ventricle. See also idiopathic hypertrophic subaortic stenosis.

subglottic stenosis stenosis of the trachea below the glottis. A congenital form results in neonatal stridor or laryngotracheitis, often requiring tracheotomy but resolving with age. An acquired form is caused by repeated intubations.

tracheal stenosis scarring of the trachea with narrowing, usually as a result of injury from an artificial airway or trauma.

tricuspid stenosis (TS) narrowing or stricture of the tricuspid orifice of the heart, a condition often seen in patients with severe congestive heart failure, usually the result of volume overload and pulmonary hypertension with right ventricular and tricuspid annular dilation.

---

renal artery stenosis

1 Acute renal arterial thrombosis 2 Arteriolonephrosclerosis, see there 3 Goldblatt kidney, see there