Takayasu arteritis

Takayasu arteritis (TA) (also known as idiopathic medial aortopathy or pulseless disease) is a granulomatous large vessel vasculitis predominantly affecting 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 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 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 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 nonspecific 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 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 it's alternative name of "pulseless disease".  

Location and 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 (i.e. descending thoracic aorta + abdominal aorta +/ - renal arteries)
• type IV - sole involvement of the abdominal aorta and/or the renal arteries
• type V - generalised involvement (all aortic segments)

Radiographic features

Ultrasound

Findings include ⁵

• homogeneous circumferential thickening of affected vessels (indistinguishable from atherosclerotic plaque)
• vascular occlusion +/- dilation
• flow velocity elevations beyond stenotic segments

CT/MRI

Findings include ²

• wall thickening - acute active phase
• wall enhancement - 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 late phase

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

Etymology

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

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 cyclosporin. Percutaneous angioplasty and bypass surgery should only be considered when there is no acute inflammation. 

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