Takayasu arteritis

Takayasu arteritis (TA),also known as idiopathic medial aortopathy or pulseless disease, is a granulomatous large vessel vasculitis that predominantly affects the aorta and its major branches. It may also affect the pulmonary arteries. The exact cause is not well known but the pathology is thought to be similar to giant cell arteritis.

Epidemiology

There is a strong female predominance (F:M ~ 9:1), increased prevalence in Asian populations, and it tends to affect younger patients (<50 years of age). The typical age of onset is at around 15-30 years of age.

Clinical presentation

It induces clinically varied ischaemic symptoms due to stenotic lesions or thrombus formation. The exact spectrum can be highly variable and dependent on the territory of vascular involvement.

Pathology

There is segmental and patch granulomatous inflammation of the aorta which results in stenosis, thrombosis and aneurysm formation. Half of the patients present with an initial systemic illness whereas the other 50% present with late-phase complications.

Two phases of the disease are classically described:

• pre-pulseless phase: characterised by non-specific systemic symptoms
• pulseless phase: presents with limb ischaemia or renovascular hypertension

The initial systemic illness may include symptoms of malaise, fever, night sweats, weight loss and arthralgia. There is often anaemia with raised inflammatory markers. This phase gradually resolves with the initiation of the chronic phase which is characterised by inflammatory and obliterative changes in the aorta and its branches. There are often reduced or absent peripheral pulses, giving rise to its alternative name of "pulseless disease".

Classification

It has been classified based on location ³:

• type I: classic type involving the solely the aortic arch branches : brachiocephalic trunk, carotid and subclavian arteries
• type II:
  • IIa: involvement of the aorta solely at its ascending portion and/or at the aortic arch +/- branches of the aortic arch
  • IIb: involvement of the descending thoracic aorta +/- ascending or aortic arch + branches
• type III: involvement of the thoracic and abdominal aorta distal to the arch and its major branches, e.g. descending thoracic aorta + abdominal aorta +/- renal arteries
• type IV: sole involvement of the abdominal aorta and/or the renal arteries
• type V: generalised involvement of all aortic segments

Radiographic features

Ultrasound

Findings include ⁵:

• long, smooth, homogeneous and moderately echogenic circumferential thickening of the arterial wall may be present; on transverse section, this finding is termed as the 'macaroni sign' and is highly specific for Takayasu arteritis (in contrast, atherosclerotic plaque is non-homogeneous, often calcified with irregular walls and generally affects a short segment)
• vascular occlusion may be seen due to intimal thickening and/or secondary thrombus formation
• flow velocities depend on the level of occlusion
• aneurysms may be noted
• there may be a loss of pulsatility of the vessel

CT/MRI

Findings include ²:

• wall thickening: active acute active phase
• wall enhancement: active acute active phase
• aortic valve disease: stenosis, regurgitation
• occlusion of major aortic branches
• aneurysmal dilatation of the aorta or its branches
• pseudoaneurysm formation
• diffuse narrowing distally (i.e. descending and abdominal aorta): in the late phase

The pulmonary arteries are also commonly involved, with the most common appearance being peripheral pruning.

Coronary findings

Described features on CTCA include ⁷:

• stenosis of the coronary ostia: ~30%
• non-ostial coronary arterial stenoses: ~35%
• coronary arterial aneurysms: ~10%

Treatment and prognosis

Treatment is with systemic steroids and judicious use of angioplasty. Corticosteroids can be used for initial treatment. Other medical options include methotrexate, cyclophosphamide, and cyclosporine. Percutaneous angioplasty and bypass surgery should only be considered when there is no acute inflammation.

Prognosis tends to variable ranging from a rapidly progressive disease in some reaching a quiescent stage in others.

History and etymology

The condition is named after Dr Takayasu (Japanese ophthalmologist) who initially described similar vascular features on the retina in 1908.