Which endoleak type is caused by retrograde flow into the native space from lumbar arteries or IMA?

Which endoleak type is caused by retrograde flow into the native space from lumbar arteries or IMA?

• A. Type I
• B. Type II
• C. Type III
• D. Type IV

Answer: (B)

The main concept is retrograde collateral flow filling the aneurysm sac after EVAR from branch vessels. A Type II endoleak occurs when blood continues to reach the aneurysm sac not from the graft ends but from collateral arteries, most commonly lumbar arteries and the inferior mesenteric artery. These vessels back-bleed into the sac, supplying it at a lower pressure than the graft, which distinguishes it from leaks that involve the graft ends themselves. This is different from a Type I endoleak, where the seal at the proximal or distal graft attachment is incomplete and high-pressure flow directly enters the sac. Type III leaks arise from defects in the graft fabric or in modular connections, letting blood enter through the graft itself. Type IV leaks result from graft porosity and are typically immediate and transient. In practice, Type II is identified by persistent or retrograde flow into the sac via these collateral vessels, and management depends on whether the sac enlarges: if it remains stable, observation may be enough; if the sac enlarges or the patient is symptomatic, targeted embolization of the feeding arteries or direct sac embolization may be performed to prevent rupture.

The main concept is retrograde collateral flow filling the aneurysm sac after EVAR from branch vessels. A Type II endoleak occurs when blood continues to reach the aneurysm sac not from the graft ends but from collateral arteries, most commonly lumbar arteries and the inferior mesenteric artery. These vessels back-bleed into the sac, supplying it at a lower pressure than the graft, which distinguishes it from leaks that involve the graft ends themselves.

This is different from a Type I endoleak, where the seal at the proximal or distal graft attachment is incomplete and high-pressure flow directly enters the sac. Type III leaks arise from defects in the graft fabric or in modular connections, letting blood enter through the graft itself. Type IV leaks result from graft porosity and are typically immediate and transient.

In practice, Type II is identified by persistent or retrograde flow into the sac via these collateral vessels, and management depends on whether the sac enlarges: if it remains stable, observation may be enough; if the sac enlarges or the patient is symptomatic, targeted embolization of the feeding arteries or direct sac embolization may be performed to prevent rupture.