The blood vessels of the body are the conduits for blood to travel to and from the heart. Arteries carry oxygen rich blood from the heart to various tissues while veins return it to the heart so that it can be routed to the lungs for oxygenation. Blood vessels are prone to many of the same diseases that affect any other tissues in the body. Although its primary function, which is the transport of blood, may be affected to varying degrees the target organs may also be impaired. This can lead to a host of signs and symptoms associated with decreased blood supply to a specific organ which is impairs its functionality.
Vasculitis is the inflammation of the blood vessels. The term arteritis is specific for inflammation of the arteries. There are may types of vasculitis, most of which are related to autoimmune diseases or infections of the blood vessels. A rare type of arteritis is Takayasu arteritis, which is known by several names including pulseless disease, aortic arch syndrome or occlusive thromboaortopathy. The arteries, particularly the large and medium arteries, are elastic to expand and recoil in a manner that keeps the blood flowing steadily through the system. This expanding and recoiling can be felt superficially as the different pulses in the body. In Takayasu arteritis, this elastic quality is lost hence the term pulseless disease.
What is Takayasu arteritis?
Takayasu arteritis is a systemic inflammatory disease of the large vessels of the body. It primarily affects the aorta and its branches. Women are eight times more likely to suffer with Takayasu arteritis and it usually starts between the ages of 25 to 30 years. Although Takayasu arteritis is seen throughout the world, it is more frequently seen in Asia. The disease is named after Dr. Takayasu who first described the disease and its effect on the retinal blood vessels.
Causes and Pathophysiology
The cause of Takayasu arteritis is unknown. However, it appears to be related to an immune mechanism known as cell-mediated immunity. Here certain types of white blood cells attack the blood vessels but is not associated with any antibody formation.
Takayasu arteritis may affect any medium to large arteries in the body but tends to affect the aorta and its branches. It has a predilection for the aortic arch and the aortic branches including the carotid, subclavian and renal arteries.The pulmonary artery, coronary and retinal arteries are also frequently affected as well. In Takayasu arteritis there is inflammation and thickening of the entire wall of the affected blood vessel. This leads to narrowing of the vessel lumen (stenosis) to varying degrees and there may even be a blockage (occlusion) particularly of the smaller vessels. An aneurysm, ballooning of the artery wall, is seen in a large number of cases.
The thickening of the vessel wall in Takayasu arteritis is irregular although it affects the entire wall. The inner layer of the artery known as the tunica intima is wrinkled. The inflammation of the wall can affect the inner vaso vasorum which supplies blood to the wall of large arteries. Chronic inflammation results in various tissue changes with formation of granulomas and even fibrous scarring of the vessel wall. These changes in the normally elastic artery wall coupled with the narrowing of the lumen affects the flow of blood. This causes the typically weak pulses observed at the periphery.
Types of Takayasu Arteritis
Based on angiographic assessment, Takayasu arteritis may be classified into six types.
- Type I – Aortic arch and its branches.
- Type IIa – Ascending aorta, aortic arch, and its branches.
- Type IIb – Areas involved in Type IIa in addition to thoracic descending aorta.
- Type III – Thoracic descending aorta, abdominal aorta, renal arteries, or a combination of these arteries.
- Type IV – Abdominal aorta, renal arteries, or both.
- Type V – Entire aorta and its branches.
Signs and Symptoms of Takayasu Arteritis
The clinical features of Takayasu arteritis may depend on the organ or part of the body that is affected by a significant reduction in blood flow (hypoperfusion) with ischemia of the area. The initial signs and symptoms of Takayasu arteritis are non-specific and include :
- Weight loss
- Night sweats
- Joint pain (arthralgia)
As the condition progresses, the clinical features of vascular inflammation become evident. This is marked by reduced blood flow which is evident as decreased blood pressure and weak pulses in the extremities (upper and lower limbs). In the legs and feet, the drastic reduction of blood flow will lead to pain, particularly upon exertion (claudication). The symptoms are not constant but fluctuate for long periods of time. These are the most prominent features in Takayasu arteritis but the vascular disturbances of other organs will lead to other features including :
- Renal artery (kidney) – high blood pressure (hypertension)
- Pulmonary artery (lung) – pulmonary hypertension presents with difficulty breathing, pale to blue skin discoloration, chest pain, dizziness, swelling of the legs.
- Coronary artery (heart muscle) – coronary artery disease (CAD) presents with angina (severe chest pain due to limited blood flow to the heart muscle) which may lead to a myocardial infarction (heart attack).
- Retinal artery (eye) – retinal hemorrhage, visual defects and even total blindness.
- Carotid and vertebral arteries (brain) – dizziness, fainting, headaches, visual disturbances, orthostatic hypotension, seizures, transient ischemic attacks (TIA’s) or a stroke.
Diagnosis of Takayasu Arteritis
Diagnosis is dependent on a history indicating impaired blood supply to an organ and the ensuing damage to tissue (ischemia). This is primarily seen in organs supplied by the aorta and its branches. The blood flow can be ascertained by a conventional angiogram, CTA (computed tomography angiography) or MRA (magnetic resonance angiography). The diagnosis of Takayasu arteritis may be difficult to make solely by the clinical features. Similar vascular changes are seen in other diseases and there is no blood test specific for Takayasu arteritis. Radiographic investigation indicating significant large artery disease with clinical features associated with Takayasu arteritis is sufficient for a diagnosis.
Treatment of Takayasu Arteritis
Long term use of corticosteroids are integral in the treatment and management of Takayasu arteritis. The use of other immunosuppressant drugs like methotrexate may be used in conjunction with corticosteroids but is reserved for more severe cases when blood flow to the heart muscle, kidney or brain is significantly compromised and worsening. Anticlotting agents are often used to avoid the formation of a blood clot which is likely to arise in the inflamed and narrowed artery.