Endoleaks

An endoleak is persistent blood flow into an aneurysm sac after endovascular aneurysm repair (EVAR) or other endovascular exclusion procedures, indicating that the sac is not completely isolated from the circulation. Endoleaks are detected during postprocedural imaging or routine follow-up and can permit ongoing sac pressurization, potentially compromising the durability of the repair.

Endoleaks are classified into several types. Type I leaks occur at the proximal or distal attachment sites and reflect inadequate seal. Type II leaks arise from retrograde flow through collateral vessels such as lumbar arteries or the inferior mesenteric artery. Type III leaks result from structural failure or separation of graft components. Type IV leaks are due to graft porosity (rare with modern devices). Type V, endotension, refers to sac expansion without identifiable flow into the sac.

Diagnosis relies on imaging, most often contrast-enhanced CT angiography, with duplex ultrasound used in some centers. Key signs include enlargement of the aneurysm sac, persistent or recurrent contrast within the sac, and changes in sac morphology. Surveillance intervals vary, but regular imaging is recommended to detect late or intermittent leaks.

Management is type-dependent. Type I and Type III leaks typically require prompt intervention to restore graft integrity or seal, through relining or extension of the graft, endovascular repair, or, in some cases, open conversion. Type II leaks are often monitored if the sac is stable; if enlargement occurs, selective embolization of feeding vessels may be performed. Type IV is rare with modern devices. Type V focuses on reducing sac pressure and may involve reassessment and possible intervention.

Prognosis depends on leak type and timing. Untreated endoleaks that maintain sac pressurization increase the risk of aneurysm growth and rupture. Early detection and appropriate management reduce risk, and improvements in graft design and surveillance have improved long-term outcomes.