Renal Vascular Disease

What is renal vascular disease?

Renal vascular disease is the name given to a variety of complications that affect the arteries and veins of the kidneys. These complications affect the blood circulation of the kidneys, and may cause damage to the tissues of the kidneys, kidney failure, and/or high blood pressure.

Vascular conditions affecting the renal arteries and veins include the following:

• Renal artery stenosis. Renal artery stenosis (RAS) is a blockage of an artery to the kidneys. It may cause kidney failure and hypertension (high blood pressure). Smokers have a greater risk of developing RAS. RAS is most common in men between the ages of 50 and 70. High cholesterol, diabetes, being overweight, and having a family history of cardiovascular disease are also risk factors for RAS. High blood pressure is both a cause and a result of RAS.

• Renal artery thrombosis. Renal artery thrombosis is the formation of a clot in a renal artery. A thrombosis of a renal artery may cause kidney failure because of blocked blood flow to the kidney.

• Renal artery aneurysm. A renal artery aneurysm is a bulging, weakened area in the wall of an artery to the kidney. Most of these aneurysms are small (less than two centimeters, or about three-quarters of an inch) and without symptoms. Renal artery aneurysms are uncommon and are generally discovered during diagnostic procedures performed in relation to other conditions.

• Atheroembolic renal disease. Atheroembolic renal disease occurs when a piece of plaque from the aorta and/or other large arteries breaks off and travels through the bloodstream, blocking small arteries such as the renal arteries. Atheroembolic renal disease is becoming a common cause of renal insufficiency (poor kidney function) in the elderly.

• Renal vein thrombosis. A renal vein thrombosis is the formation of a clot in a vein to the kidney.

Renal vascular disease is often associated with hypertension (high blood pressure). Hormones which influence blood pressure are affected by kidney function. Decreased blood flow to the kidney(s) as a result of renal vascular disease may cause an excessive amount of renin to be produced. Renin is a powerful hormone that increases blood pressure.

What causes renal vascular disease?

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The cause of renal vascular disease will depend on the specific condition involved:

• Renal artery stenosis. Stenosis (blockage) of a renal artery may be caused by atherosclerosis (a build-up of plaque, which is a deposit of fatty substances, cholesterol, cellular waste products, calcium, and fibrin in the inner lining of an artery) or other conditions, such as fibromuscular dysplasia (a condition that weakens the walls of medium-sized arteries and occurs predominantly in young women of childbearing age), and Takayasu's arteritis (a rare inflammatory disease affecting the aorta and its branches, including the renal arteries). Atherosclerosis is the major cause of renal artery stenosis in the U.S.

• Renal artery thrombosis. Formation of a thrombosis (clot) inside one of the renal arteries may occur as a result of trauma, infection, inflammatory disease, renal artery aneurysm, renal cell cancer, or fibromuscular dysplasia.

• Renal artery aneurysm. There are four types of renal artery aneurysms:

  • Saccular. These bulge or balloon out on only one side of the artery.

  • Fusiform. These bulge or balloon out on all sides of the artery.

  • Dissecting. This type is a weakened artery wall due to a tear in the inner layer of the artery wall.

  • Intrarenal. These occur on an artery inside the kidney.

  Saccular aneurysms may occur as a result of a congenital (present at birth) weakness of an artery wall or trauma. Atherosclerosis may also be a factor. Fusiform aneurysms most often occur with fibromuscular dysplasia. Intrarenal aneurysms may be congenital, or may result from trauma.

• Atheroembolic renal disease. Small pieces of plaque (emboli) from atherosclerosis formation in other arteries of the body may break off and travel to the renal arteries, blocking blood flow to the kidney. Emboli may occur because of surgery, insertion of a catheter, or the use of blood-thinning medications. The disease most commonly affects older persons.

• Renal vein thrombosis. Conditions associated with the presence of renal vein thrombosis include trauma, compression of a renal vein by an adjacent structure such as a tumor or aneurysm, nephrotic syndrome (results from damage to the kidneys' glomeruli, the tiny blood vessels that filter waste and excess water from the blood and send them to the bladder as urine), pregnancy, and administration of steroid medications.

Risk factors for renal vascular disease include:

• Age

• Female gender

• Atherosclerosis

• Hypertension, particularly new onset of hypertension in an older person

• Smoking

• High cholesterol

• Diabetes

A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking or diet, family history, or many other things. Different diseases have different risk factors.

Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. Knowing your risk factors for any disease can help to guide you to the appropriate actions, including changing behaviors and being clinically monitored for the disease.

What are the symptoms of renal vascular disease?

Symptoms of renal vascular disease vary depending on the type of disease and degree of involvement present. Symptoms of various types of renal vascular disease include, but are not limited to, the following:

The symptoms of renal vascular disease may resemble other medical conditions or problems. Always consult your physician for a diagnosis.

How is renal vascular disease diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for renal vascular disease may include any, or a combination of, the following:

• Arteriogram (also called an angiogram). An x-ray image of the blood vessels used to evaluate various conditions, such as aneurysm, stenosis (narrowing of the blood vessel), or blockages. A dye (contrast) will be injected through a thin, flexible tube placed in an artery. This dye makes the blood vessels visible on x-ray.

• Duplex ultrasound. A type of vascular ultrasound procedure performed to assess blood flow and the structure of the leg veins. The term "duplex" refers to the fact that two modes of ultrasound are used -- Doppler and B-mode. The B-mode transducer (like a microphone) obtains an image of the carotid artery being studied. The Doppler probe within the transducer evaluates the velocity and direction of blood flow in the vessel.

• Renography. A specialized radiology procedure used to assess the function and structure of the kidneys. Renography is a type of nuclear radiology procedure. This means that a tiny amount of a radioactive substance is used during the procedure to assist in the examination of the kidneys.

• Magnetic resonance angiography (MRA). A noninvasive diagnostic procedure that uses a combination of magnetic resonance imaging (MRI) technology and intravenous (IV) contrast dye to visualize blood vessels. Contrast dye causes blood vessels to appear opaque on the MRI image, allowing the physician to visualize the blood vessels being evaluated.

What is the treatment for renal vascular disease?

Specific treatment will be determined by your physician based on:

• Your age, overall health and medical history

• Extent of the disease

• Your signs and symptoms

• Your tolerance for specific medications, procedures, or therapies

• Expectations for the course of the disease

• Your opinion or preference

Treatment will also vary depending on the type of renal vascular disease that is present.