, David G. I. Scott2 and Chetan Mukhtyar2
(1)
Department of Rheumatology, Ipswich Hospital NHS Trust, Ipswich, UK
(2)
Department of Rheumatology, Norfolk and Norwich University Hospital, Norwich, UK
6.1 Introduction
Takayasu arteritis (TA) is a granulomatous vasculitis of unknown etiology occurring in young people and is characterized by stenosis, occlusion, and sometimes aneurysm formation of large arteries. TA has various names including pulseless disease, aortic arch syndrome, long-segment atypical coarctation of the aorta, Martorell’s syndrome, and occlusive thromboaortopathy. The first full description of the natural history and pathology of Takayasu arteritis was provided by Sir William Savory in 1856. He described a 13 month in-patient stay of a 22 year old woman with obliteration of the carotid and subclavian arteries. He attributed the autopsy appearances of the arteries to an inflammatory condition [1].
6.2 Definition and Classification
The Chapel Hill consensus conference defined TA as “Arteritis, often granulomatous, predominantly affectingthe aorta and/or its major branches. Onset usually in patients younger than 50 years” [2].
The ACR in 1990 developed the classification criteria which are widely used in clinical trials. The presence of any three or more criteria yields a sensitivity of 90.5 % and specificity of 97.8 % [2] (Table 6.1).
Table 6.1
ACR classification criteria for TA
Age <40 years old |
Development of symptoms or signs related to TA at age <40 years |
Claudication of extremities |
Development and worsening of fatigue and discomfort in muscles of one or more extremity while in use, especially the upper extremities |
Decreased brachial arterial pulse |
Decreased pulsation of one or both brachial arteries |
BP difference >10 mmHg |
Difference of >10 mmHg in systolic blood pressure between arms |
Bruit over subclavian arteries or aorta |
Bruit audible on auscultation over one or both subclavian arteries or abdominal aorta |
Arteriogram abnormality |
Arteriographic narrowing or occlusion of the entire aorta, its proximal branches, or large arteries in the proximal upper or lower extremities, not due to atherosclerosis, fibromuscular dysplasia, or similar causes; changes usually focal or segmental |
6.3 Epidemiology
TA occurs throughout the world and may have a varying clinical spectrum in different populations. TA is believed to be predominantly found in Asia, the Middle East and South America. Patients with TA have been increasingly recognized in Africa, Europe, and North America. The incidence in Europe and USA is 0.5–2.5/million/year [4–6]. In Japan, the incidence is probably much higher. In an autopsy study, Hotchi describes the frequency of TA in 0.033 % of all autopsies [7]. Most series report a female preponderance. Symptom onset is typically aged less than 40 years, with a median age of onset 25–30 years.
6.4 Etiology
The strong racial distribution of the disease may be genetic, but it does not have to be. Although, familial forms of TA have been described, the disease does not have strong inheritance. IL12B region on chromosome 5, MLX region on chromosome 17, and HLA-B*52:01 have been shown to be significant associations for TA [8]. IL12B region seems to play an important part in the pathophysiology. It exhibits a synergistic effect when co-present with HLA-B*52:01 in increasing the risk of TA. IL12B region also demonstrates an association with aortic regurgitation in TA [8]. The IL12B association has been verified in a separate multi-ethnic cohort [9]. Two additional HLA susceptibility loci have been identified at HLA-DQB1/HLA-DRB1 and HLA-B/MICA [9].
6.5 Clinical Features
6.5.1 Systemic
Systemic symptoms may be present in up to 20–40 % of patients and include fatigue weight loss, night sweats, fever, arthralgia, and myalgia.
6.5.2 Vascular
At the time of diagnosis, approximately 20 % of patients with TA have no vascular symptoms, with the disease being detected by abnormal clinical findings. The most common findings at presentation are absence or asymmetry of peripheral pulses, claudication of arm or legs, transient visual disturbance, scotoma, blurring, or diplopia.
On physical examination, the most common features are diminished or absent pulses, bruits, and asymmetric blood pressure measurements between extremities. Carotidynia (tenderness of the carotid arteries) is rare but characteristic. Hypertension occurs in approximately 28 % of patients with TA and is due to coarctation of the aorta or renal artery stenosis.
6.6 Laboratory Features
The most common laboratory finding is the presence of elevated inflammatory markers (ESR and/or CRP) and a blood picture reflective of acute inflammation. There may be a normochromic normocytic anemia with leukocytosis and thrombocytosis.
6.6.1 Immunology
TA is not associated with the presence of ANCA, RF, ANA, and anticardiolipin antibodies.
6.6.2 Imaging
Since 2004, there have been several case series demonstrating the utility of physiological imaging in the form of 18-fluorodeoxyglucose (FDG) labeled positron emission tomography (PET) (Fig. 6.1) [10]. The advantage of this modality over conventional computed tomography (CT) or magnetic resonance (MR) angiography is its ability to demonstrate intramural inflammation which precedes luminal changes. PET-CT scanning is now the accepted modality for the diagnosis of TA. However the radiation exposure of approximately 25 mSv and the inability of the modality to correlate with disease activity mean that it is not a good modality for monitoring of disease activity.
