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, claudication and absence of femoral pulses ¹¹.

Classification

The anatomical location of atheromatous lesions influence the classification and treatment choice ¹²:

• type I: confined to distal abdominal aorta and common iliac arteries
• type II: as above with extension into the external iliac arteries
• type III: aortoiliac segment and femoropopliteal vessels

According to the Trans Atlantic Inter Society Consensus II (TASC II) Leriche syndrome is a type D lesion ¹³.

Pathology

The condition can be acute or chronic. There is endothelial damage resulting in inflammation and lipid accumulation in the tunica media and macrophages eventually leading to plaque formation and occlusive disease ¹¹. Complete infra-renal aortoiliac occlusion will display significant collateral circulation sustained by multiple anastomoses allowing reconstitution with the distal femoral arteries ¹³.

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.

Etiology

• 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/occlusion, the commonest collateral pathways to the lower extremities are ⁵:

• superior mesenteric artery > inferior mesenteric artery > superior rectal artery >
  • middle and inferior rectal arteries > internal iliac arteries ¹⁰
  • obturator / internal pudendal arteries > common femoral arteries ¹⁰
• 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 Pathway ⁷)

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 visualization 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) 
  • patency rates of 90% at five years and 80% at ten years ¹¹
  • Tasc II type D lesions recommend surgery as the treatment of choice ¹³
• axillobifemoral bypass (extra-anatomic technique); used to avoid abdominal surgery
• percutaneous transluminal angioplasty (PTA) and stenting

Other more novel methods include

• covered endovascular reconstruction of aortic bifurcation (CERAB) technique

History and etymology

It is named after French vascular surgeon René Leriche (1879–1955) 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)