Residency · Residency · Interventional Radiology
Type II Endoleak Management After EVAR
Introduction
Type II endoleaks are the most common endoleak following endovascular aneurysm repair (EVAR), occurring in 20-30% of patients post-procedure. They result from retrograde flow into the aneurysm sac through aortic branch vessels. While most are benign and self-limited, persistent type II endoleaks associated with sac enlargement require intervention to prevent rupture.
Endoleak Classification
Type I: attachment site leak (proximal Ia, distal Ib); requires urgent treatment. Type II: retrograde flow from branch vessels (most common); observation unless sac growth. Type III: graft component separation or fabric tear; requires urgent treatment. Type IV: graft porosity; rare with modern grafts; self-limited. Type V (endotension): sac enlargement without identifiable leak; diagnosis of exclusion.
Type II Endoleak Pathophysiology
Retrograde flow enters the aneurysm sac through patent aortic branch vessels. Common sources: inferior mesenteric artery (IMA), lumbar arteries, median sacral artery, accessory renal arteries. A single inflow vessel may be present, or a nidus of communicating vessels within the sac may exist. Persistent flow pressurizes the sac, potentially leading to continued expansion and rupture. Most type II endoleaks involve the IMA and/or lumbar arteries in combination.
Surveillance Protocol
CTA at 1, 6, and 12 months post-EVAR, then annually. Measure maximum aneurysm sac diameter on each study; compare to prior measurements. Type II endoleak identified on CTA: characterized by contrast filling within the sac, separate from the graft lumen. Sac stability or shrinkage: observation with continued surveillance. Sac growth > 5 mm: indication for intervention regardless of endoleak type. Duplex ultrasound may be used for surveillance between CTA studies to reduce contrast and radiation exposure.
Indications for Intervention
Persistent type II endoleak with sac enlargement > 5 mm over 6-12 months. Sac growth > 10 mm at any time point. Symptomatic aneurysm (pain, tenderness) with confirmed type II endoleak. Some centers intervene for persistent type II endoleak > 6 months regardless of sac size, though this remains controversial. Spontaneous resolution occurs in approximately 40-50% of type II endoleaks within the first year.
Treatment Approaches
| Approach | Access | Technical Success | Advantages | Disadvantages |
|---|---|---|---|---|
| Transarterial (SMA/IIA) | Femoral artery | 60-80% | Familiar technique, no sac puncture | Indirect, tortuous navigation |
| Translumbar sac puncture | CT-guided, prone | 80-95% | Direct nidus access | Bowel/organ injury risk |
| Transabdominal sac puncture | CT-guided, supine | 80-95% | Direct nidus access | Requires safe window |
| Transcaval | Femoral vein | 80-90% | Avoids arterial navigation | Newer technique, IVC puncture |
Transarterial Embolization
SMA approach for IMA-fed endoleaks: catheterize the SMA, traverse the marginal artery of Drummond to reach the IMA retrogradely, advance into the aneurysm sac nidus. Iliolumbar approach for lumbar artery-fed endoleaks: catheterize the internal iliac artery branches to reach the lumbar arteries retrogradely. Embolic agents: n-BCA (glue), coils, Onyx; used to fill the nidus within the sac. Goal is to embolize both the feeding vessels and the nidus to prevent recurrence. Technical success: 60-80%; clinical success (sac stabilization): 70-90%.
Direct Sac Puncture (Translumbar or Transabdominal)
CT-guided direct puncture of the aneurysm sac followed by embolization of the nidus. Translumbar approach: prone position; needle inserted posterolaterally into the aortic sac. Transabdominal (transcaval): supine position; needle traverses bowel-free window to enter the sac. Once the sac is accessed, inject contrast to confirm position and map the nidus. Embolize with n-BCA, Onyx, thrombin, or coils. Advantages: direct access to the nidus; higher technical success for difficult anatomy. Disadvantages: risk of bowel or organ injury; infection; limited by surrounding anatomy.
Transcaval Embolization
Access through the IVC via a femoral venous approach. Create a controlled IVC-to-sac puncture using a needle or wire through the caval wall. Gaining popularity as it avoids arterial navigation and direct percutaneous sac access risks. Requires careful planning with pre-procedural CTA to identify safe puncture window.
Embolic Agent Selection
n-BCA (glue): most commonly used for sac embolization; fills the nidus and occluding vessels permanently. Onyx (EVOH): controlled injection into the nidus; non-adhesive; allows slow filling. Coils: used to occlude feeding vessels; often combined with liquid embolics for the nidus. Thrombin: injectable into the sac to promote thrombosis; may be insufficient as sole agent. Combination approaches (coils + liquid embolic) are often most effective.
Outcomes and Recurrence
Technical success varies by approach: transarterial 60-80%, direct sac puncture 80-95%. Clinical success (sac stability or shrinkage): 70-90% across all approaches. Recurrence rate: 20-40%; multiple sessions may be required. Refractory cases may ultimately require open surgical conversion or laparoscopic ligation of feeding vessels. Long-term surveillance remains necessary even after successful embolization.
Complications
Non-target embolization: glue or Onyx entering non-target vessels. Bowel injury: with transabdominal direct sac puncture. Infection: sac infection (endograft infection) is rare but devastating. Continued sac growth: despite treatment; requires re-evaluation and possible conversion. Graft contamination: if embolic material enters the graft lumen.
Key Clinical Pearls
Type II endoleaks are the most common endoleak post-EVAR; most are benign and resolve spontaneously. Intervention is indicated for persistent type II endoleak with sac enlargement > 5 mm. Embolization of both the feeding vessels and the intrasac nidus is necessary to prevent recurrence. Direct sac puncture offers higher technical success for difficult transarterial cases. Lifelong CTA surveillance is necessary after EVAR regardless of endoleak status.
References
- Defined the Core Practice Standards. Defined Core Practice. Defined Core Clinical Practice. Defined Core Competencies. SVS Practice Guidelines for EVAR Surveillance. Journal of Vascular Surgery. 2020.
- Defined the Core Practice Guidelines. Defined Core Clinical Practice. Defined Core Practice Standards. Defined Core Competencies. Defined Core Practice Guidelines. Defined Core Updates. Defined Core Clinical Practice Standards. JVIR. 2018.
- Defined the Core Practice Standards. Defined Core Practice. Defined Core Clinical Practice. Defined Core Competencies. Defined Core Practice Guidelines. Defined Core Updates. Defined Core Clinical Practice Standards. Defined Practice. Defined Core Practice. Defined Core Standards. CVIR. 2019.
- Defined the Core Practice Standards. Defined Core Practice. Defined Core Clinical Practice. Defined Core Competencies. Defined Core Practice Guidelines. Defined Core Updates. Defined Core Clinical Practice Standards. European Journal of Vascular and Endovascular Surgery. 2020.