Takayasu's arteritis

Takayasu's arteritis (TA), also known as Takayasu's disease, aortic arch syndrome, nonspecific aortoarteritis, and pulseless disease, is a rare, chronic form of large-vessel granulomatous vasculitis that causes inflammation in the walls of major arteries. The disease affects the aorta (the main blood vessel leaving the heart) and its branches, as well as the pulmonary arteries.

Inflammation can lead to narrowing (stenosis), occlusion (complete blocking), or weakening and dilution (aneurysm) of affected arteries, restricting blood flow and leading to symptoms such as limb claudication, hypertension, and neurologic or visual disturbances.

Takayasu's arteritis most commonly affects young or middle-aged women, particularly those of Asian descent, though it can occur in any population. Females are approximately 8–9 times more likely to be affected than males. Because of the involvement of the aortic arch branches, physical examination may reveal absent or weakened pulse in the arms, hence the term "pulseless disease."

In the Western world, atherosclerosis is a more common cause of large vessel obstruction particularly in older individuals, whereas Takayasu's arteritis is more frequently seen in younger patients and may resemble other vasculitides such as giant cell arteritis.

Some people develop an initial "inflammatory phase" characterized by systemic illness with signs and symptoms of malaise, fever, night sweats, weight loss, joint pain, fatigue, and fainting. Fainting may result from subclavian steal syndrome or carotid sinus hypersensitivity. There is also often anemia and marked elevation of the ESR or C-reactive protein (nonspecific markers of inflammation). The initial "inflammatory phase" is often followed by a secondary "pulseless phase". The "pulseless phase" is characterized by vascular insufficiency from intimal narrowing of the vessels manifesting as arm or leg claudication, renal artery stenosis causing hypertension, and neurological manifestations due to decreased blood flow to the brain.

Of note is the function of renal artery stenosis in the causation of high blood pressure: Normally perfused kidneys produce a proportionate amount of a substance called renin. Stenosis of the renal arteries causes hypoperfusion (decreased blood flow) of the juxtaglomerular apparatus, resulting in exaggerated secretion of renin, and high blood levels of aldosterone, eventually leading to water and salt retention and high blood pressure. The neurological symptoms of the disease vary depending on the degree; the nature of the blood vessel obstruction; and can range from lightheadedness to seizures (in severe cases).

One rare, important feature of the Takayasu's arteritis is ocular involvement in form of visual field defects, vision loss, or retinal hemorrhage. Some individuals with Takayasu's arteritis may present with only late vascular changes, without a preceding systemic illness. In the late stage, weakness of the arterial walls may give rise to localized aneurysms. As with all aneurysms, the possibility of rupture and vascular bleeding is existent and requires monitoring. In view of the chronic process and good collateral development, Raynaud's phenomenon or digital gangrene are very rare in Takayasu arteritis.

Laser Doppler imaging by near-infrared digital holography can reveal characteristic blood flow waveforms in the central artery and vein of the retina in patients with vascular insufficiency who may exhibit a smooth systo-diastolic pulse in the central retinal artery. This technique enables non invasive functional microangiography by high-contrast measurement of endoluminal blood flow profiles in vessels in the posterior segment of the eye with a spatial resolution comparable to state-of-the-art indocyanine green angiography.^{[citation needed]}