Unusual Case of Chest and Left Arm Pain

DISCUSSION

The first description of TA is credited to Japanese ophthalmologist Mikito Takayasu, who in 1908 described a wreathlike arteriovenous anastomosis around the optic disc of a 21-year-old woman who had experienced acute vision loss.^1-3 Much earlier, in 1761, Italian anatomist Giovanni Battista Morgagni described large-vessel aneurysms and stenosis on a postmortem exam of a 40-year-old woman.^2,4 However, TA was not formally labeled a disease until 1975.

TA is a chronic large vessel vasculitis of unknown origin, mainly involving the aorta and its primary branches: the left common carotid, brachiocephalic, and left subclavian arteries. Ongoing inflammation of affected vessels causes fibrotic changes, stenosis, and eventual occlusion and may lead to aneurysm formation.^5,6 TA is rare, with an annual incidence in North America of 2.6 cases per million population.⁶ It occurs most frequently in Asian countries but has been reported in a wide range of ethnic groups.^5,7 TA has been characterized as a disease of young women: Between 80% and 97% of patients are women,^6,8 and the average age at diagnosis is 25 to 30.^8-10

The process of vascular injury in TA begins with inflammation in the vasa vasorum of the aortic vessels. This inflammation, thought to be triggered by an as-yet-unknown antigen, leads to an initial inflammatory cellular infiltration of the aortic media and adventitia; the infiltrate is comprised predominantly of macrophages and T cells.^5,9 Inflammatory infiltration causes myointimal proliferation, thickening of the blood vessel wall, and eventual luminal stenosis.⁵ Cytokines, interleukin 6, interferon , and other chemokines released by infiltrating inflammatory cells within the injured tissue also contribute to the inflammatory response and tissue damage.^5,11

Histologically, granulomatous inflammation and giant cells are found in the media.^12,13 Destruction of the elastic lamina and the muscular media results in the aneurysmal dilation seen in TA, while dense scarring and continued inflammation of the arterial vasculature results in arterial stenosis.¹²

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