musculoskeletal and connective tissue disorders
Takayasu Arteritis
Diagnosis of Takayasu Arteritis
Magnetic resonance angiography, sometimes CT angiography or aortic arteriography The diagnosis of Takayasu arteritis is suspected when symptoms suggest ischemia of organs supplied by the aorta or its branches or when peripheral pulses are decreased or absent in patients at low risk of atherosclerosis and other aortic disorders, especially in young women. In these patients, arterial bruits and right/left or upper extremity/lower extremity discrepancies in pulses or in blood pressure (BP) also suggest the diagnosis. Confirmation of the diagnosis used to require aortic arteriography; however, now magnetic resonance angiography or CT angiography can be used instead to evaluate all branches of the aorta. Characteristic findings include stenosis, occlusion, irregularities in arterial lumens, poststenotic dilation, collateral arteries around obstructed vessels, and aneurysms. BP is measured in all extremities. However, accurate measurement of BP can be difficult. If both subclavian arteries are severely affected, systemic BP can be accurately measured only in the legs. If the disorder affects both subclavian arteries and patients have coarctation of the descending aorta and/or involvement of both iliac or femoral arteries, BP cannot be accurately measured in any limb. Then, central arterial pressure must be measured via angiography to detect occult hypertension, which can cause complications. Other clues to occult hypertension can be funduscopic signs of hypertensive retinopathy and/or echocardiographic signs of concentric left ventricular hypertrophy. When severe hypertension is not recognized, complications can be confused with signs of vasculitis causing organ ischemia. Laboratory tests are nonspecific and not helpful in diagnosis. Common findings include anemia of chronic disease, elevated platelet levels, occasionally elevated white blood cell counts, and elevated erythrocyte sedimentation rate and C-reactive protein. The following are indicators of disease activity in Takayasu arteritis: Symptoms and signs: New systemic symptoms (eg, fever, fatigue, weight loss, anorexia, night sweats), symptoms suggesting vasculitis involving new arterial territories (eg, claudication), new bruits, and/or new changes in BP measurements Laboratory tests: Evidence of inflammation detected by blood tests (although markers of inflammation may be normal in active arteritis) Imaging studies: Development of stenosis or aneurysms in previously unaffected arteries (assessed with periodic imaging [usually magnetic resonance angiography]) However, Takayasu arteritis can progress silently even when clinical and laboratory studies suggest complete remission. Therefore, periodic imaging of the aorta and large arteries is mandatory. BP should be measured regularly in an unaffected limb. Disorders that mimic Takayasu arteritis must be excluded. They include Inherited noninflammatory connective tissue disorders (eg, Ehlers-Danlos Syndromes or Vascular infections (tuberculous, fungal, or syphilitic) Fibromuscular dysplasias Disorders causing arterial thrombosis (eg, hypercoagulable states) Idiopathic inflammatory conditions (eg, Ankylosing Spondylitis with aortitis, All of these disorders can affect large vessels. 