Endoleak after EVAR

Axial CT images of the same level during precontrast, arterial phase and delayed phase of enhancement show an endoleak at the right posterolateral aspect of the endovascular stent graft (arrow). The endoleak was visualized only in the delayed image. Aortic wall calcification noted in all images (arrowheads).

Facts: Endoleak

• One of the complications of endovascular aortic aneurysm repair (EVAR)
• Blood flow external to the stent-graft and inside the aneurysm sac
• Aneurysm sac communicates with the systemic circulation, most commonly, through reversal of flow through aortic branch vessels
• Difficult to diagnose and treat, management remains a controversy
• Classification system organizes endoleak into 5 types based on "source of blood flow"
• Most common type of endoleak after abdominal aortic aneurysm repair = type II, in which retrograde blood flow through aortic branch vessels into the aneurysm sac. Typical sources = inferior mesenteric and lumbar arteries.

Types of Endoleak

• I = attachment site leak (either proximal or distal)
• II = collateral-vessel leak
• III = graft failure - midgraft hole, junctional leak, or disconnect
• IV = graft-wall porosity
• V = endotension

Imaging Surveillance

• Lifelong imaging surveillance required after EVAR
• Ideal frequency not well defined, but usually done at 1 and 6 months after initial repair - then every 6 months thereafter
• CT angiography most widely used, multiphase is recommended
• Endoleaks have variable flow rates, therefore they can be detected at variable times after contrast administration. Some can be detected only on arterial phase or delayed phase (as in our case)

Reference:

Stavropoulos SW, Charagundla SR. Imaging techniques for detection and management of endoleaks after endovascular aortic aneurysm repair. Radiology 2007;243:641-655.