Aortoiliac occlusive disease

Aortoiliac occlusive disease refers to complete occlusion of the aorta distal to the renal arteries.

Terminology

When the clinical triad of impotence, pelvis and thigh claudication, and absence of the femoral pulses are present, it may also be called Leriche syndrome, which usually affects younger (30-40 year old) males ⁹.

Clinical presentation

Aortoiliac occlusive disease is more common in the elderly with an advanced atherosclerotic disease. Acute onset is more common in female patients and is associated with poor outcome with approximately 50% mortality.

In acute cases, symptoms include the 6 Ps :

• pain
• pulselessness
• pallor
• paresthesia
• paralysis
• prostration 

In chronic onset cases, mostly in arteriosclerosis, symptoms may include erectile dysfunction or impotence.

Pathology

The condition can be acute or chronic.

Location

Most often the occlusion occurs near the aortic bifurcation. It typically begins at the distal aorta or common iliac artery origins and slowly progresses proximally and distally over time.

Aetiology

• arteriosclerosis: the main cause of this syndrome is an atherosclerotic obstruction of aortoiliac arteries ²
• vasculitis
• thrombosis

An extensive network of collateral parietal and visceral vessels may form to bypass any segment of the aortoiliac arterial system. In abdominal aortoiliac stenosis and occlusion, the most commonly occurring collateral pathways to the lower extremities are ⁵

• superior mesenteric artery > inferior mesenteric artery > superior rectal artery > middle and inferior rectal arteries > external iliac arteries
• intercostal, subcostal, and lumbar arteries > superior gluteal and iliolumbar arteries > internal iliac arteries > external iliac arteries. 
• intercostal, subcostal, and lumbar arteries > circumflex arteries > external iliac arteries
• subclavian arteries > internal thoracic (mammary) arteries > superior epigastric arteries > inferior epigastric arteries > external iliac arteries (the Winslow Pathway⁷)

Radiographic features

CT angiography is usually the best modality for assessment. In patients where CT is not possible, contrast-enhanced MR angiography may be a good option ⁴.

CT angiography

It allows direct anatomical visualisation of the location of the stenosis and occlusion. It also permits the assessment for the presence of a concomitant occlusive disease affecting visceral arteries, the type and extent of collateralization, and the level of the most proximal and distal arterial segments amenable to stent-graft placement.

Treatment and prognosis

Traditional surgical procedures for aortoiliac occlusive disease are ⁸ :

• aortoiliac endarterectomy (TEA)
• aortobifemoral bypass (AFB) 
• axillobifemoral bypass (extra-anatomic technique); used to avoid abdominal surgery
• percutaneous transluminal angioplasty (PTA) and stenting

History and etymology

It is named after French surgeon René Leriche who initially described the findings in 1948 ³.

Differential diagnosis

Imaging differential considerations include:

• mid-aortic syndrome: occurs at or above renal artery level with the involvement of a longer segment and usually in much younger patients (usually 10-30 years old)