What is Takayasu's arteritis?
Arteritis is a general term that refers to the inflammation of arteries, or blood vessels (vasculitis), that carry blood away from the heart.
Takayasu's arteritis (TAK) is an uncommon form of vasculitis. Inflammation damages large, and medium-sized blood vessels. The vessels most commonly affected are the branches of the aorta (the main blood vessel that leaves the heart), including the blood vessels that supply blood to the arms and travel through the neck to provide blood to the brain. The aorta itself is also often affected.
Segments of blood vessels can weaken and stretch, resulting in an aneurysm. They can also become inflamed and narrowed, resulting in restricted blood flow. Lastly, blood vessels can become completely blocked (called an occlusion).
Less commonly, arteries that provide blood flow to the heart, intestines, kidneys and legs may be involved.
Inflammation of large blood vessels may cause segments of the vessels to weaken and stretch, resulting in an aneurysm. Vessels can also become narrowed or even completely blocked (called an occlusion).
Who is affected by Takayasu's arteritis ?
TAK often affects young Asian women, but it can affect children, women and men of all ages and ethnic backgrounds. At diagnosis, TAK patients are often between 15-35 years old.
Every year in the United States, two to three new cases of TA per million Americans are diagnosed.
Symptoms and Causes
What are the symptoms of Takayasu's arteritis ?
Approximately half of all patients with TAK will have a sense of generalized illness. This may include fevers, fatigue, muscle aches, pain in the joints, and/or headaches. Narrowed vessels cause decreased blood flow to the areas that are supplied "downstream" from the narrowed area.
The changes that occur in TAK are often gradual, allowing alternate (or collateral) routes of blood flow to develop. These alternate routes are often smaller "side roads." The collateral vessels may or may not be adequate to carry as much blood as was present normally.
In general, the blood flow that occurs beyond an area of narrowing is almost always adequate to allow tissues to survive. In rare cases, if collateral blood vessels are not available in sufficient quantity, the tissue that is no longer supplied by blood and oxygen will die. This is called an "infarction."
Narrowing of blood vessels to the arms or legs may cause fatigue, pain, or aching due to reduced blood supply -- especially during activities such as shampooing the hair, exercising or walking. It is much less common for decreased blood flow to cause a stroke or a heart attack (myocardial infarction). In some patients, decreased blood flow to the intestines may lead to abdominal pain, especially after meals.
Decreased blood flow to the kidneys may cause high blood pressure, but rarely causes kidney failure.
Some patients with TAK may not have any symptoms. Their diagnosis may be stumbled upon by a doctor who has difficulty measuring blood pressure in one or both arms. Similarly, a doctor may notice that the strength of pulses in the wrists, neck or groin may not be equal, or the pulse on one side may be absent.
What causes TAK?
The exact cause of TAK is unknown.
Diagnosis and Tests
How is Takayasu's arteritis diagnosed?
The diagnosis of TA is based on a combination of factors, including:
- Complete medical history and careful physical exam to exclude other illnesses that may have similar symptoms
- X-rays, which show location and severity of vessel damage
- Procedures to detect blood vessel narrowing or aneurysm, including:
Magnetic resonance imaging (MRI): a test that produces images of the human body without the use of X-rays. MRI uses a large magnet, electromagnetic energy waves and a computer to produce these images.
Computed axial tomography (CAT scan): X-rays and computers are used to produce images of internal organs, including large blood vessels.
Angiography: X-ray pictures of the inside of blood vessels. During angiography, a long slender tube called a catheter is inserted into a large artery (generally, in the groin area or arm). The catheter is slowly and carefully threaded through the artery until its tip reaches the segment of vessel to be examined. A small amount of contrast material is injected into the blood vessel through the catheter, and X-rays are taken. The contrast agent enables the blood vessels to appear on the X-ray pictures.
- Significant narrowing of blood vessels may result in turbulent blood flow through the narrowed area that creates an unusual sound called a bruit.
Note: With most other forms of vasculitis, a biopsy (tissue sample) of the affected area may confirm the presence of blood vessel inflammation. A biopsy is most appropriate when easily accessible areas, such as the skin, are affected. However, when large blood vessels are affected, a biopsy is often not practical because of the risks of surgery.
Management and Treatment
How is Takayasu's arteritis treated?
Corticosteroids are the most common treatment for TAK. The most frequently used drug in this category is prednisone or prednisolone. Corticosteroids work within hours after the first dose is given. While this drug is often dramatically effective in bringing about remission (the absence of active blood vessel inflammation), it may be only partially effective for some patients and it may not prevent TAK from coming back (called a relapse).
The goal of therapy is to stop all injury due to vasculitis. Once it is apparent that the disease is under control, doctors slowly reduce the dose of prednisone to the lowest effective dose in order to minimize treatment side effects. In some patients, it is possible to gradually discontinue medication without a relapse.
As the dose of prednisone is gradually reduced, over half of all patients will have recurrent symptoms or progression of illness. This has led to exploring additional therapies to produce remission. Among drugs that have been tried, with varying degrees of success, are immunosuppressive medications such as methotrexate, azathioprine (Imuran®), mycophenolate (Cellcept® or Myfortic®), or rarely cyclophosphamide (Cytoxan®) . Preliminary reports also suggest encouraging results with use of certain biologic agents. These experiences will have to be confirmed in formal studies before they can be generally recommended.
When these drugs are added to prednisone to treat TAK, 50% of patients who had previously relapsed will achieve remission and be able to gradually discontinue prednisone. Overall, about 25% of patients will have disease that is not entirely controlled without continued use of these therapies. This emphasizes the need for continuing research to identify better and less toxic treatments for TAK and other forms of vasculitis.
Many patients with TAK have high blood pressure (hypertension). Careful control of blood pressure is very important. Inadequate treatment of high blood pressure may result in stroke, heart disease, or kidney failure.
In some instances, narrowing of arteries to the kidney may be the cause of hypertension. Whenever possible, it is desirable to stretch narrow vessel openings with a balloon (angioplasty) or to do a bypass operation to restore normal flow to the kidney. This may result in normal blood pressure, without the need to use antihypertensive medications.
Some patients may have serious disabilities because of narrowed blood vessels to other sites such as the arms or legs. Bypass operations may correct these abnormalities. Aneurysms can also be surgically repaired or bypassed.
Outlook / Prognosis
What is the outlook for patients with Takayasu's arteritis?
In the United States and Japan, only about 3% of patients with Takayasu's arteritis die after having the disease for an average period of 5 years. This encouraging statistic is the product of recognizing the disease and treating it appropriately. Reports from certain other parts of the world have been less optimistic. This may be the result of delayed recognition and treatment or poor access to care.
For patients who live long lives, in spite of having Takayasu's disease, there are significant problems that must be recognized. Having a chronic illness requires periodic evaluation and adjustment of drugs whenever necessary. The drugs for TAK have side effects, and these must be monitored by a doctor, as well as by blood tests. The effects of illness on function may be significant.
In our experience, 25% of patients have an entirely normal lifestyle. Another 25% have had to make some adjustments in their activities. About half of our patients had to modify their jobs and some within that group were occupationally disabled.
TAK is clearly a treatable disease, and most patients improve. However, it is apparent that many patients have to deal with consequences of this illness that may be partially, or less often, completely disabling. These effects can be minimized by a team of doctors that includes specialists in vascular and immunologic diseases (rheumatology, immunology, radiology, vascular medicine, vascular and cardiac surgery). For best results, a team leader should coordinate diagnostic tests and the different forms of treatment that TAK patients may require.