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 that 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?

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 buildup 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 people.
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, administration of steroid medications, and use of oral contraceptives (birth control pills).

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:

TYPE OF RENAL VASCULAR DISEASE	SYMPTOMS
Renal artery stenosis	Sudden onset of hypertension before age 50 suggests fibromuscular dysplasia-related stenosis Sudden onset of hypertension at or after age 50 suggests stenosis caused by atherosclerosis. Hypertension not responsive to three or more blood pressure medications. Increased urea (a waste product excreted by the kidneys) in the blood. Unexplained kidney failure. Sudden kidney failure when first taking an angiotensin-converting enzyme (ACE) inhibitor medication for blood pressure and/or heart treatment
Renal artery thrombosis	Acute (sudden) complete blockage: Sudden onset of flank (between the ribs and the upper border of the hip bone) pain and tenderness Fever Blood in the urine Nausea and/or vomiting Sudden decrease in kidney function Hypertension More gradual or incomplete blockages: May be asymptomatic (without symptoms) and go undetected
Renal artery aneurysm	Generally asymptomatic Hypertension may be present in up to 90 percent of persons with a renal artery aneurysm Dissecting aneurysms (caused by a tear in the inner layer of the artery wall) may cause flank pain and blood in the urine
Atheroembolic renal disease	Skin lesions such as purpura (a type of rash in which blood cells leak into the skin or mucous membranes) Mottling (discolored areas) of the toes and feet Kidney failure (either sudden or occurring over a longer period of time) Abdominal pain Diarrhea Confusion Weight loss Fever Muscle aches
Renal vein thrombosis	Chronic (over a period of time) onset: Most often asymptomatic Acute (sudden) onset: Persistent severe flank pain that may be spasmodic (with spasms) at times Soreness in the area over the kidney, between the ribs and the backbone Decreased kidney function

The symptoms of renal vascular disease may resemble other medical conditions or problems. Always consult your doctor 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 doctor to visualize the blood vessels being evaluated.

What is the treatment for renal vascular disease?

Specific treatment will be determined by your doctor 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.

TYPE OF RENAL VASCULAR DISEASE	TREATMENT
Renal artery stenosis	Medical treatment: Antihypertensive medications other than ACE inhibitors may be used to treat high blood pressure. In stenosis caused by atherosclerosis, medications to lower cholesterol may be prescribed. Treatment of related medical conditions such as diabetes. Surgical treatment: Endovascular procedures such as angioplasty (the opening of a renal artery using a balloon or other method) or placement of a stent (a tiny, expandable metal coil placed inside an artery to keep the artery open). Open surgical procedures to bypass the occluded renal artery. There are several variations of such procedures.
Renal artery thrombosis	Treatment of a renal artery thrombosis depends on the type (acute or chronic) of thrombosis, and the length of time since the thrombosis occurred. In acute situations, thrombolytic (clot-busting) medication may be infused into the renal artery for several hours to several days to break up the clot. Surgery to remove the clot or bypass the artery may be performed in some situations.
Renal artery aneurysm	Treatment of a renal artery aneurysm depends on factors such as the size and location of the aneurysm and whether or not symptoms are present. Certain types of small (less than two centimeters, or about three-quarters of an inch) aneurysms may not be treated, but may be observed for growth or development of other complications. Larger aneurysms (greater than two centimeters or three-quarters of an inch), dissecting aneurysms, aneurysms causing kidney ischemia (lack of blood flow to the kidney tissue) and hypertension, aneurysms that are growing larger, and aneurysms causing symptoms may be treated surgically. Because of the increased risk for rupture (bursting), a renal artery aneurysm in a pregnant woman or a woman of childbearing age will generally be treated surgically.
Atheroembolic renal disease	Treatment of atheroembolic renal disease depends on the extent of the disease and the individual situation. Medical treatment may include medications to reduce cholesterol, blood pressure, and other related medical conditions, such as diabetes. Surgical treatment may include: Endovascular procedures such as angioplasty (the opening of a renal artery using a balloon or other method) or placement of a stent (a tiny, expandable metal coil placed inside an artery to keep the artery open). Open surgical procedures to bypass the occluded renal artery. There are several variations of such procedures.
Renal vein thrombosis	Renal vein thrombosis is generally treated medically with anticoagulant (keeps the blood from clotting) medication. Anticoagulants may be given intravenously (IV) for several days, then given orally for several weeks up to an indefinite period of time.