Atheroembolic renal disease

Definition

Atheroembolic renal disease (AERD) refers to an inflammatory reaction in the small blood vessels of the kidneys. It occurs when cholesterol crystals from atherosclerotic plaques (lipid and cholesterol plaques in the walls of blood vessels) break off and move to the kidneys. It often results in irreversible damage to the kidney tissue. If severe enough, it may result in end stage renal disease.

Causes, incidence, and risk factors

AERD results from atherosclerotic plaque, the source of cholesterol crystals. A diseased, atherosclerotic aorta is the most common cause of AERD. The syndrome is most often begins following direct mechanical injury to the plaque, causing the release of the cholesterol crystals into the blood stream. Thus, cardiac catheterization is a common cause, as is direct injury during aortic surgery.

Thrombolysis or anticoagulation (a process of making the blood thin so as to avoid clot formation in some disease states) has been known to agitate the plaques and release cholesterol crystals. Rarely, the syndrome may occur spontaneously.

Once in the circulation, the crystals lodge in small blood vessels. As the aorta is the most common source of the crystals, the kidney, intestine and legs are at prime risk.

Once in the tiny blood vessels called arterioles, the crystals cause an intense inflammatory response. The end result is organ damage due to decreased blood supply. In the kidneys, this may lead to acute renal failure if the reaction is severe.

A spectrum of responses may be seen, though. These range from serious end stage renal disease, requiring dialysis, to only mild elevation in plasma creatinine (a test used to gauge kidney function).

The risk factors for AERD are the same as risk factors for atherosclerosis. This is a syndrome seen predominantly in elderly males with vascular disease.

Symptoms

AERD may not have any symptoms. However, it can cause the following:

• Foot pain, ulcers on the feet, or “blue toes” (due to decreased blood flow to the feet and toes)
• Pain in the abdomen, nausea or vomiting (due to decreased blood flow to the intestine)
• Pancreatitis (inflammation of the pancreas) or hepatitis (inflammation of the liver), although these are rare
• Strokes or blindness
• Flank pain and blood in the urine (rare)
• Uncontrolled high blood pressure

Kidney failure may result in the following:

• Nausea or vomiting
• Loss of appetite
• Weight loss
• Decreased or no urine output
• Swelling
• Decrease in sensation
• Skin pigment changes
• Dry itchy skin
• Drowsiness, confusion, lethargy

Signs and tests

An examination may show swelling of the whole body. Examination of the eyes may show particles in the small arteries of the retina. Evidence of fluid overload may develop if kidney failure is present, including abnormal sounds when listening to the heart and lungs with a stethoscope. A loud whooshing sound called a bruit, for example, may be heard over the aorta or renal artery.

Blood pressure may be elevated, and the patient may have a history of hard-to-control high blood pressure. There may be multiple ulcers of the skin of the lower feet.

These tests help diagnose the disorder:

• Blood, protein, eosinophils, or other abnormality in a urinalysis.
• CBC abnormal (eosinophilia, thrombocytopenia ).
• Serum complement may be low.
• Serum lipids may be high.
• Accumulation of nitrogen wastes in the blood if kidney failure develops:
  • BUN elevated.
  • Creatinine elevated.
• Increased potassium or other abnormality in serum chemistry (chem-7 or chem-20 ).
• A kidney or abdominal ultrasound, abdominal CT scan, abdominal MRI, or abdominal x-ray may be abnormal. Medical dyes or special techniques may be used to enhance the images, such as in magnetic resonance angiography.
• Renal arteriography may show blockage.
• Kidney biopsy or biopsy of other suspect tissue may show changes indicating atheroembolic disease.

Treatment

Treatment goals vary depending on what the doctor finds and the severity of symptoms.

Medicines may include medicine to treat high blood pressure and to lower serum lipid/cholesterol levels. Other treatments for renal failure or other complications may be appropriate.

Taking care of yourself is important to reduce progression of the disorder. You may need to reduce fats and cholesterol in your diet. If you have renal failure, you may need to restrict protein, salt, and fluids, or make other dietary changes. Your doctor may also recommend other lifestyle changes. Stopping smoking is extremely important, increasing exercise, weight loss, and a variety of other things may also help.

Expectations (prognosis)

The outcome varies but is generally poor. The disorder is often long-term and progressive. Lifestyle changes may help slow progression of the disease.

Complications

• Acute renal failure
• Chronic renal failure
• High blood pressure
• Blood clots to other location of the body -- brain, intestine, legs

Calling your health care provider

Call your doctor if urine output drops or stops, or if blood is seen in the urine.

Call your doctor if you have severe abdominal pain or leg pain, unexplained ulcers appear on your legs or feet, or your toes turn purple and you get foot pain.

Prevention

You can alter the factors that increase your risk of getting this disease. You should lose weight if you are obese, decrease or stop smoking, and follow your doctor's recommendations to control diabetes or high blood pressure. Reducing fats, especially saturated fats, in your diet may help to reduce serum lipid levels.

Illustrations

Male urinary system

Page Content:

Renal disease - atheroembolic; Cholesterol embolization syndrome; Atheroemboli - renal; Atherosclerotic disease - renal