Overview
Definition:
An endoleak is defined as persistent blood flow into the aneurysm sac outside of the endograft lumen after endovascular aneurysm repair (EVAR)
It represents an incomplete seal between the endograft and the native aorta, posing a risk for continued sac pressurization and potential aneurysm rupture.
Epidemiology:
Endoleaks are the most common complication after EVAR, occurring in approximately 10-20% of patients in the early postoperative period
Type II endoleaks are the most frequent, while Type I and Type III have higher risks of sac enlargement and rupture.
Clinical Significance:
Endoleaks are critically important as they can lead to continued sac pressurization, aneurysm sac enlargement, graft migration, and ultimately, a higher risk of late rupture
Early identification and appropriate management are essential for long-term EVAR success and patient safety.
Endoleak Classification
Type I:
Flow into the aneurysm sac from the proximal or distal attachment sites of the endograft
Type IA involves the proximal seal
Type IB involves the distal seal
This type is associated with high sac pressures and significant rupture risk.
Type Ii:
Retrograde flow into the aneurysm sac from patent branch arteries (e.g., lumbar, mesenteric, internal iliac arteries)
These are the most common type and may be hemodynamically insignificant, but can also cause sac enlargement.
Type Iii:
Disruption of the endograft fabric or modular connections, allowing blood flow into the sac
Type IIIA results from fabric tear or delamination
Type IIIB from disconnection of modular components.
Type Iv:
Leak through the porous graft material itself
This type is less common with modern grafts but can occur.
Type V:
Endotension, characterized by continued sac expansion without demonstrable endoleak on imaging
This may be due to endotension or an unidentified leak.
Diagnostic Approach
History Taking:
Focus on any new or increasing abdominal or back pain, pulsating abdominal mass, or symptoms suggestive of limb ischemia
Patients are typically followed with surveillance imaging.
Physical Examination:
Palpation for pulsatile abdominal masses or tenderness
Auscultation for abdominal bruits
Examination for peripheral pulses and signs of limb ischemia.
Investigations:
Surveillance imaging is key
Duplex ultrasound is often the initial screening tool
however, CT angiography (CTA) is the gold standard for definitive diagnosis, characterization, and monitoring of endoleaks
MRI angiography (MRA) and digital subtraction angiography (DSA) may also be used
Imaging should assess graft integrity, position, and sac size.
Differential Diagnosis:
Aneurysm sac enlargement without endoleak (endotension), graft thrombosis, infection, graft migration, or aortoenteric fistula.
Management Principles
Initial Management:
The management strategy depends on the type of endoleak, its hemodynamic significance, and the presence of aneurysm sac enlargement
A multidisciplinary approach involving vascular surgeons and interventional radiologists is often employed.
Type I And Iii Management:
These leaks are considered high risk and typically require urgent reintervention
Options include repeat EVAR with oversizing or extending the graft, chimney/fenestrated grafts, or conversion to open surgical repair if endovascular options are not feasible.
Type Ii Management:
Management is debated and depends on sac behavior
Small, stable sacs with Type II leaks from lumbar arteries may be observed
Symptomatic Type II leaks or those associated with sac growth often require intervention
Options include embolization of feeding arteries via radiology, transabdominal coil embolization, or surgical ligation of feeding vessels.
Type Iv Management:
Typically requires reintervention, similar to Type I and III, as it indicates a breach in graft integrity and potential for sac pressurization
Options include graft repair or replacement.
Type V Management:
Management is challenging and often involves re-imaging to detect occult leaks
If no leak is found and sac expansion persists, options may include further embolization or conversion to open repair.
Follow Up
Surveillance Imaging:
Regular imaging (CTA or duplex ultrasound) is crucial for all EVAR patients
Initial surveillance is typically performed at 1 month, 6 months, and then annually, or more frequently if an endoleak is present or suspected.
Endoleak Monitoring:
Patients with identified endoleaks require closer monitoring
The frequency of follow-up is determined by the type of endoleak, its hemodynamic significance, and the presence of sac enlargement.
Reintervention Criteria:
Reintervention is generally indicated for Type I, III, and IV endoleaks
Type II endoleaks associated with sac expansion >5mm over 6 months
or any endoleak with a rapidly expanding sac, suggestive of impending rupture.
Key Points
Exam Focus:
Understand the specific characteristics and associated rupture risks of each endoleak type
Master the indications for intervention for each type, especially the differentiating factors for Type II leaks.
Clinical Pearls:
Always correlate imaging findings with clinical presentation
Distinguish between true endoleaks and artifacts
Consider the feasibility of endovascular versus open repair for complex cases.
Common Mistakes:
Underestimating the risk of Type II leaks leading to sac expansion and rupture
Delaying intervention for Type I and III leaks
Inadequate imaging for diagnosis and follow-up
Failing to consider endotension as a diagnosis.