Takayasu's arteritis overview

# Overview
In Takayasu's arteritis, the most commonly involved vessels include the left subclavian artery (50%), left common carotid artery (20%), brachiocephalic trunk, renal arteries, celiac trunk, superior mesenteric artery, and pulmonary arteries (50%). Infrequently, the axillary, brachial, vertebral, coronary, and iliac arteries are involved. The pathogenesis of Takayasu's arteritis is poorly understood. Takayasu's arteritis characterized by segmental and patchy granulomatous inflammation of the aorta and its major derivative branches.This inflammation leads to arterial stenosis, thrombosis, and aneurysms. Three factors that have been suggested to have association with susceptibility, development and progression of Takayasu's arteritis are genetic influences, immunologic mechanisms and relationship to tuberculosis. The cause of Takayasu's arteritis is idiopathic but genetic, immunologic and infectious factors play important role in the development of Takayasu's arteritis. Takayasu arteritis has a worldwide distribution, it is observed more frequently in Asian countries such as Japan, Korea, China, India, Thailand, and Singapore. Female are more commonly affected. Common risk factors in the development of Takayasu's arteritis include genetic predisposition, female sex, age 10 mm Hg) between arms. Hypertension due to renal artery involvement is found in approximately 50% of patients. Absent or diminished pulses are the clinical hallmark of Takayasu arteritis. Chest radiographs may reveal widening of the ascending aorta, irregular descending aorta, aortic calcifications, and rib notching (late findings). Most people with Takayasus arteritis respond to steroids such as prednisone. The usual starting dose is approximately 1 milligram per kilogram of body weight per day (for most people, this is approximately 60 milligrams a day). The two most important aspects of treatment: are controlling the inflammatory process and controlling hypertension.

# Historical Perspective
In 1830, Rokushu Yamamoto, who practised Japanese oriental medicine described the first case of Takayasus arteritis. In 1905, Mikito Takayasu repoted a case of a 21 year old woman with characteristic fundal arteriovenous anastamoses as a case of peculiar changes in the central retinal vessels. In 1905, Onishi and Kagosha reported cases associated with absent radial pulses.

# Classification
Takayasu arteritis may be classified according to angiographic findings into 6 subtypes. These systems are useful in that they allow a comparison of patient characteristics according to the vessels involved and are helpful in planning surgery, but they offer little by way of prognosis. The most commonly involved vessels include the left subclavian artery (50%), left common carotid artery (20%), brachiocephalic trunk, renal arteries, celiac trunk, superior mesenteric artery, and pulmonary arteries (50%). Infrequently, the axillary, brachial, vertebral, coronary, and iliac arteries are involved.

# Pathophysiology
The pathogenesis of Takayasu's arteritis is poorly understood. Takayasu's arteritis characterized by segmental and patchy granulomatous inflammation of the aorta and its major derivative branches.This inflammation leads to arterial stenosis, thrombosis, and aneurysms. Three factors that have been suggested to have association with susceptibility, development and progression of Takayasu's arteritis are genetic influences, immunologic mechanisms and relationship to tuberculosis.

# Causes
The cause of Takayasu's arteritis is idiopathic but genetic, immunologic and infectious factors play important role in the development of Takayasu's arteritis.

# Differentiating Rheumatoid Arthritis from other Diseases
Takayasu's arteritis should be distinguished from other conditions that cause arthritis and rash.

# Epidemiology and Demographics
Takayasu arteritis has a worldwide distribution, it is observed more frequently in Asian countries such as Japan, Korea, China, India, Thailand, and Singapore. The incidence of Takayasu arteritis is approximately 0.26 per 100,000 individuals worldwide. Female are more commonly affected by Takayasu arteritis than male. Mean age of onset of Takayasu arteritis is approximately 30 years.

# Risk Factors
Common risk factors in the development of Takayasu's arteritis include genetic predisposition, female sex, age <40, asian ethnicity.

# Screening
According to the United States Preventive Services Task Force (UPSTF), screening for Takayasu's arteritis is not recommended.

# Natural History, Complications and Prognosis
The symptoms of Takayasu's arteritis typically develop between 15 and 30 years of age. Common complications of Takayasu's arteritis include hardening and narrowing of blood vessels, High blood pressure, Heart failure, Stroke, Transient ischemic attack. The five year survival rate in Takayasu arteritis is over 90%.

# Diagnosis

## History and Symptoms
Common symptoms of Takayasu's arteritis include headache, malaise, arthralgias, bruit, claudication, hypertension, visual disturbance. Less common symptoms of Takayasu's arteritis include fever, weight loss, carotodynia or vessel tenderness, Raynaud's syndrome, stroke, transient ischemic attacks, seizures, erythema nodosum.

## Physical Examination
A thorough physical examination is essential, with particular attention to peripheral pulses, blood pressure in all 4 extremities, ophthalmologic examination. The most common finding is a systolic blood pressure difference (>10 mm Hg) between arms. Hypertension due to renal artery involvement is found in approximately 50% of patients. Absent or diminished pulses are the clinical hallmark of Takayasu arteritis, but pulses are normal in many patients and upper limbs are affected more often Than lower limbs. Ophthalmologic examination may show retinal ischemia, Retinal hemorrhages, cotton-wool exudates, venous dilatation and beading, microaneurysms of peripheral retina, optic atrophy, vitreous hemorrhage, wreathlike peripapillary arteriovenous anastomoses.

## Laboratory Findings
There are no diagnostic laboratory tests for Takayasu's arteritis. Testing for acute phase reactants such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may provide additional support for the presence of a systemic inflammatory process; Normochromic normocytic anemia suggestive of the anemia of chronic disease.

## Electrocardiogram
There are no ECG findings associated with Takayasu's arteritis.

## X Ray
Chest radiographs may reveal widening of the ascending aorta, irregular descending aorta, aortic calcifications, and rib notching (late findings).

## Echocardiography and Ultrasound
Echocardiography may be helpful in the diagnosis of Takayasu's arteritis and its complications. Findings on an echocardiography suggestive of Takayasu's arteritis include aortic regurgitation. Doppler ultrasound is a useful non-invasive procedure for the assessment of vessel wall inflammation in patients with Takayasu's arteritis. Ultrasonography is limited by operator-dependent artefacts from overlying structures and bowel gas. In Takayasu's arteritis, ultrasound can be helpful in detecting sub-millimeter changes in wall thickness of the carotid arteries.

## CT
CT scan manifestations in Takayasu arteritis include mural thickening (typical manifestation), calcification in the thickened wall and double ring enhancement pattern.

## MRI
MRI can demonstrate mural thickening with luminal stenosis of the aorta and branching vessels of the aortic arch. It can directly visualize the vessel wall independent of luminal diameter and can be helpful in diagnosis of inflammation in early vasculitis.

## Other Imaging Findings
PET scan is useful in diagnosis of Takayasu's arteritis by providing valuable information about cellular activity within an inflamed arterial wall even before morphologic changes on other imaging studies. In patients with TA, MRA shares the similar features of TA with CTA images, and can be used in the diagnosis and follow-up of patients undergoing treatment, especially those who are young.

## Other Diagnostic Studies
There are no other diagnostic studies associated with Takayasu's arteritis.

# Treatment

## Medical Therapy
Most people with Takayasus arteritis respond to steroids such as prednisone. The usual starting dose is approximately 1 milligram per kilogram of body weight per day (for most people, this is approximately 60 milligrams a day). The two most important aspects of treatment: are controlling the inflammatory process and controlling hypertension.

## Surgery
Surgical options may need to be explored for those who do not respond to steroids. Re-perfusion of tissue can be achieved by large vessel reconstructive surgery such as bypass grafting.

# Prevention

## Primary Prevention
There are no established measures for the primary prevention of Takayasu's arteritis.

## Secondary Prevention
Diet modification is necessary to manage hypertension or renal failure in Takayasu's arteritis. Any activity limitations depend on the severity of the disease and complications.

## Future or Investigational Therapies

# Reference