TA is a relatively rare chronic inflammatory and stenotic disease that mainly affects the aorta and its main branches (the brachiocephalic, carotid, subclavian, vertebral, and renal arteries), although the coronary and pulmonary arteries can be affected as well. A worldwide incidence of 0.4–2.6 cases per million annually has been reported. However, it is observed more frequently in Asian countries and Central and South America. Approximately 80% of patients with TA are female and the mean age of onset is approximately 30 years .
Although the etiology is unknown, the underlying pathologic process of TA is inflammatory. It is associated with an inflammatory cellular infiltrate in the aortic media, adventitia, and vasa vasorum that consists predominantly of lymphocytes, macrophages, and multinucleated giant cells. Advanced lesions demonstrate a panarteriitis with intimal proliferation. Over time, scarring of the aortic wall and destruction of the elastic lamina occurs.
As laboratory tests are nonspecific for TA, imaging studies such as CT scanning and magnetic resonance imaging may show typical patterns of stenoses or aneurysms of the arteries. However, angiography remains the cornerstone for diagnosis and evaluation of the extent of disease. TA can be divided into the following six types based on angiographic involvement: (a) Type I—branches of the aortic; (b) Type IIa—ascending aorta, aortic arch, and its branches; (c) Type IIb—Type IIa region plus thoracic descending aorta; (d) Type III—thoracic descending aorta, abdominal aorta, renal arteries, or a combination; (e) Type IV—abdominal aorta, renal arteries, or both; and (f) Type V—entire aorta and its branches . Tissue biopsy does not play an important role in the diagnosis of TA, as histologic examination of the great vessels is usually possible only at the time of vascular surgery or postmortem.
Our patient had stenoses of all aortic arch arteries and previous surgical bypasses, with the coronary arteries unaffected (Type I). Cerebral perfusion was being maintained by the collateral circulation including an unusual and large collateral from the sinoatrial artery. Development of a collateral circulation can be seen in TA’s third stage of quiescence due to the chronic nature of the illness. Moreover, neurological manifestations can be observed in about 20% of cases and are predominantly ischemic in nature due to stenoses of the vessels. A CT cerebrum in our patient showed multiple demarcated hypodense regions in both cerebral hemispheres as a consequence of previous strokes but without signs of recent ischemia. The episodic (postural) neurological dysfunction likely caused by cerebral hypoperfusion eventually led to recurrent (near)-syncope. In general, complications of TA may include the following: cerebrovascular accidents, seizures, ischemia, organ failure, complications of hypertension, or graft stenoses and/or occlusion. In patients with two or more complications, the 5- and 10-year survival rates are estimated to be 69% and 36%, respectively. In patients with one or no complication, it is estimated to be 100% and 96%, respectively [1, 4]. Strict management of traditional cardiovascular risk factors is mandatory to minimize secondary cardiovascular complications. Our patients has had several vascular complications, multiple strokes, seizures, and graft occlusions. She remained a heavy smoker as multiple attempts to quit smoking failed, which may have contributed to the failure of the aorta–carotid graft. In the active stage of TA, glucocorticoid treatment aims to halt the inflammation and prevent development of stenoses in the arteries. When the response to steroids is inadequate, cytotoxic agents such as methotrexate, azathioprine, and cyclophosphamide can be used. Moreover, anti-tumor necrosis factor (TNF) agents have shown encouraging results but further evaluation is needed. Critical stenotic lesions can be treated by bypass graft surgery providing good long-term patency rate. Percutaneous balloon angioplasty may serve as an alternative in case of short lesions. The use of conventional stents seems to be associated with high failure rates in patients with TA.