Type 1 and 2 endoleaks: causes and management
An endoleak (endoleak, leak) is the persistence of blood flow within the aneurysm sac outside the deployed aortic stent-graft.
Type 1 is caused by inadequate sealing (seal) between the device and the vessel wall. There is type 1A (proximal end) and type 1B (distal end). This is caused by device migration, sizing errors, or unfavorable neck morphology (e.g., mural atheromatosis). The pathology causes a constant pressure increase in the sac and threatens rupture. Requires mandatory treatment: proximal or distal endograft extension, cuff placement, endoanchors (endoanchors), or balloon angioplasty.
Type 2 occurs due to retrograde filling of the sac from small unoccluded side branches (intercostal, lumbar arteries, inferior mesenteric artery). This does not require immediate intervention: surgery is indicated only with documented aneurysm sac expansion. It is treated with transcatheter embolization using liquid embolic systems (e.g., Onyx) or direct CT-guided percutaneous embolization.
Type 3, 4, and 5 endoleaks
Other types of leaks are related to the material or design of the prosthesis itself:
- Type 3: occurs due to disconnection of modular graft components or fabric tears. Requires placement of additional overlapping (overlapping) endografts to close the defect.
- Type 4: transient porosity (porosity) of the graft material, equivalent to "sweating" of knitted surgical grafts. Does not require treatment.
- Type 5 (endotension): continued sac enlargement in the absence of a visible endoleak. Characteristic of older graft types. Treated with relining (relining) with additional stents or device explantation.
Device migration, kinking, and occlusion
With each heartbeat, blood flow exerts significant stress on the stent-graft, tending to displace it distally in the direction of blood flow.
Device migration, as well as long-term aortic morphological changes (narrow diameter, tortuosity), can lead to limb kinking (limb kinking). This threatens local thrombosis, lumen occlusion, distal vascular embolization, and loss of seal leading to type 1 or 3 endoleaks.
The incidence of such complications with modern devices is 1–2%. Additional stent-grafts are placed to correct migration, and in cases of severe kinking, bare metallic stents (bare metallic stents) are deployed within the endograft lumen.
Endoprosthesis infection and fistulas
Stent-graft infection (graft infection) is a rare complication accompanied by fluid collections and periaortic abscesses (including in the psoas muscle — psoas collection). On CT angiography, signs of infection include inflammatory stranding of the periaortic adipose tissue and gas within the sac beyond the early postoperative period. Treatment includes percutaneous drainage and antibiotic therapy.
One of the most severe complications is aortoenteric fistulas (aortoenteric fistulas). They can be the cause or consequence of infection. Clinical practice describes cases of enteroaortoenteric fistula formation due to erosion of the aortic wall by a deployed duodenal stent. This presents with intermittent gastrointestinal bleeding. Emergency EVAR combined with prolonged antibiotic therapy is used to isolate the fistula.
Diagnostic radiology
EVAR complications require a multidisciplinary approach and careful imaging surveillance. Main imaging modalities:
- CT angiography (CTA): gold standard, confirms contrast accumulation in the sac and its anatomical connection with aortic branches, visualizes fistulas and gas.
- Power Doppler US: used to assess the direction of blood flow from collaterals.
- Contrast-enhanced ultrasound (CEUS): clearly demonstrates contrast extravasation outside the stent-graft limbs.
Briefly: answers to topical questions
What anatomical features of the aneurysm neck are contraindications to standard EVAR?
Unfavorable anatomical features of the aneurysm neck that limit standard endovascular repair include:
- Barrel-shaped neck (barrel neck) below the renal arteries.
- Short conical neck (short conical neck); the distance from the proximal aneurysm neck to the lower renal artery is less than 15 mm.
- Angulation — neck angulation in the anteroposterior and lateral planes greater than 60 degrees.
- Severe atheromatous wall changes, including mural atheromatosis.
Conical shape and severe atheromatous changes can impair proximal apposition and sealing, while an angle greater than 60 degrees increases the risk of stent migration.
What is the imaging semiotics of a type 2 endoleak on contrast-enhanced ultrasound (CEUS)?
During contrast-enhanced ultrasound, a type 2 endoleak is visualized as a contrast agent accumulation within the aneurysm.
The contrast agent is clearly identified in the anterior parts of the aneurysm sac. At the same time, it is located outside the stent-graft limbs (stent-graft limbs). Such an imaging pattern confirms retrograde filling of the sac from collateral aortic branches, such as the inferior mesenteric or lumbar arteries, which were not occluded during the endovascular procedure.
Causes of endoleaks by type: 1 — ends (junction detachment), 2 — branches (retrograde flow), 3 — prosthesis itself (tear or disconnection), 4 — pores (seepage), 5 — swelling without apparent causes (endotension).
Class and exam questions
Why does a type 1 endoleak require mandatory surgical intervention?
In type 1, the seal between the stent-graft and the aortic wall is compromised. This leads to direct systemic pressure on the aneurysm sac walls, its rapid expansion, and an extremely high risk of fatal rupture.
Is a type 2 endoleak always in need of surgery?
No. In 50% of cases, it resolves spontaneously within 12 months. Intervention (embolization) is indicated only if follow-up imaging demonstrates an increase in aneurysm sac dimensions.
How is a stent-graft limb kinking corrected?
In case of a significant stenotic kink (kinking) into the lumen of the endograft at the site of narrowing, additional supporting bare-metal stents are placed.
What else to study on this topic
- Comparison of long-term outcomes of EVAR and open surgical repair (EVAR trial 1, DREAM, OVER trials)
- Use of fenestrated and branched endoprostheses in juxtarenal aneurysms
- Emergency endovascular treatment of traumatic thoracic aortic injuries (TEVAR)
- Technique of direct CT-guided percutaneous embolization of an endoleak
- Protocols for lifelong imaging surveillance of patients after EVAR
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