Endovascular interventions for abdominal aortic aneurysm (EVAR)

Q: Which specific aortic branches most commonly become the source of a type II endoleak?

Sources of type II endoleaks are small collateral branches of the aorta, from which retrograde blood flow into the aneurysm sac occurs. Such vessels include: - Intercostal arteries. - Lumbar arteries. - Inferior mesenteric artery.

Q: What are the absolute contraindications for endovascular abdominal aortic repair (EVAR)?

Absolute contraindications to endovascular aortic repair include conditions where risks outweigh benefits or the procedure is technically impossible. The following absolute contraindications are distinguished: - Lack of patient consent — a fundamental legal limitation. - Limited life expectancy — if the risks of the intervention outweigh the potential benefit. - Low cardiopulmonary reserve — presence of severe comorbid conditions. - Unstable patients — if the condition does not allow withstanding delays for imaging. - Pathology of the ascending aorta — except in cases where there is no surgical alternative.

Q: What endovascular techniques are used to treat stenoses and occlusions of the aortic bifurcation?

Minimally invasive endovascular techniques are used to treat stenoses and occlusions of the aorta, including those extending into the iliac arteries. These include: - Balloon angioplasty — dilation of the narrowed segment. - Primary aortic stenting — placement of a stent in the affected segment. - Use of "kissing" balloons or stents — a technique applied from the aorta to the common iliac arteries.

Q: Which visceral arteries require blood flow preservation during the deployment of fenestrated stent-grafts (FEVAR)?

When deploying fenestrated stent grafts, blood flow is preserved through fenestrations to the following arteries: - Superior mesenteric artery (SMA) — using covered stents. - Renal arteries — using covered stents.

Q: At what abdominal aortic aneurysm size is surgery indicated?

Intervention (open or EVAR) is indicated once the aneurysm diameter reaches 5.5 cm or more. Below this size, surgical risks outweigh the risk of rupture, so surveillance is maintained.

Q: What is a type II endoleak and does it need immediate treatment?

This is blood leakage into the aneurysm sac from side branches (retrograde). In most cases, it is simply monitored and treated (embolized) only if the aneurysmal sac begins to enlarge.

Q: What is the issue with the internal iliac artery in endovascular treatment?

It often has to be embolized to prevent a type II endoleak. However, unilateral embolization can lead to intermittent claudication of the gluteal muscles and erectile dysfunction.

Anatomical criteria for stent-graft placement

For successful stent-graft implantation, the anatomy of the proximal neck (the segment from the lower renal arteries to the aneurysm) and the distal landing zone is critically important.

Proximal zone: The neck length should be >8–15 mm. Acceptable angulation (bending) is <75° (<45° in the suprarenal segment), and the diameter ranges from 17 to 32 mm. A short or tortuous neck dramatically increases the risk of failure and blood leakage (endoleak). For reliability, bare-metal stents may be placed over the ostia of the renal arteries.
Distal landing zone: This is typically the common iliac artery. A length of 10–20 mm and a diameter of 8–22 mm are required.
Branch management: To prevent retrograde blood flow, the internal iliac artery is sometimes embolized, but this carries the risk of buttock claudication and erectile dysfunction. A modern solution is iliac branched devices that preserve pelvic blood flow.

Management of abdominal aortic aneurysm (AAA)

AAAs are most often asymptomatic. The risk of rupture is directly related to the diameter.

Action algorithm:

Less than 5.5 cm: Dynamic monitoring is indicated. Operating at small sizes carries a higher mortality rate than conservative management.
5.5 cm and greater: Surgical or endovascular intervention is indicated.

In ruptured AAA (rAAA), mortality exceeds 85%. Emergency EVAR requires CT for planning, which consumes precious time, but in the long term (3 years) yields better quality-of-life outcomes compared to open surgery. Aortic balloon occlusion can be used as a temporary lifesaving measure.

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Specific complications: Endoleaks

The main issue with endovascular interventions is endoleaks (endoleak), which is the persistence of blood flow within the aneurysmal sac outside the stent-graft. Due to these, patients require lifelong CT or ultrasound monitoring.

Type I: Lack of seal at the graft margins (1A — proximal, 1B — distal). Requires mandatory treatment (extension, cuff placement).
Type II: Retrograde flow from side branches. Observation is frequently chosen; if the sac enlarges, the branch is embolized.
Type III: Defect of the stent-graft itself or separation of its components. Always requires repair (additional internal stent-graft — relining).
Type IV: Porosity of the graft material (seepage). Virtually absent in modern devices and requires no treatment.
Type V (Endotension): The aneurysm continues to grow despite the absence of visible contrast extravasation. Explantation or complete sealing of the graft from within is indicated.

Complex cases and other interventions

Thoracoabdominal aortic aneurysms (TAAAs): Involve visceral branches. Their treatment utilizes complex custom-built stent-grafts: fenestrated (FEVAR, featuring ports for vessels where covered stents are placed) and branched. Despite excellent technical success, risks of paraplegia (6%) and renal failure (15%) persist.
Aortic stenoses and occlusions: Rare. Treated with angioplasty and stenting (including the "kissing" balloons technique at the bifurcation). This is an outpatient procedure or requires a 1-day hospital stay. 5-year patency for isolated stenosis reaches 100%.
Trauma: In blunt abdominal trauma (deceleration mechanism in traffic accidents) with aortic rupture or dissection, EVAR is the preferred strategy.

Briefly: answers to topical questions

Which specific aortic branches most commonly become the source of a type II endoleak?

Small side branches of the aorta, from which retrograde blood flow into the aneurysmal sac occurs, become the sources of type II endoleaks. Such vessels include:

Intercostal arteries.
Lumbar arteries (lumbar arteries).
Inferior mesenteric artery (inferior mesenteric artery).

What are the absolute contraindications for endovascular abdominal aortic repair (EVAR)?

Absolute contraindications for endovascular repair include conditions where the risks outweigh the benefits, or the procedure is technically impossible. The following absolute contraindications are distinguished:

Lack of patient consent (Lack of patient consent) — a fundamental legal limitation.
Limited life expectancy — when the risks of intervention outweigh the potential benefits.
Low cardiopulmonary reserve — the presence of severe comorbid conditions.
Unstable patients — when the condition does not allow withstanding the delay for imaging.
Pathology of the ascending aorta — except in cases where no surgical alternative exists.

What endovascular techniques are used to treat stenoses and occlusions of the aortic bifurcation?

Minimally invasive endovascular techniques are used to treat aortic stenoses and occlusions, including those extending into the iliac arteries. These include:

Balloon angioplasty — dilation of the narrowed segment.
Primary aortic stenting — placement of a stent in the affected segment.
Use of kissing balloons or stents (kissing) — a technique applied from the aorta to the common iliac arteries.

Which visceral arteries require blood flow preservation during the deployment of fenestrated stent-grafts (FEVAR)?

During the deployment of fenestrated stent-grafts, blood flow is preserved through fenestrations in the following arteries:

Superior mesenteric artery (SMA) — using covered stents.
Renal arteries — using covered stents.

How to memorize

How to easily remember endoleak types: 1 — Edge defect (entry/exit), 2 — Branches (retrograde flow), 3 — Crack (graft fracture), 4 — Pores (seepage), 5 — Endotension (sac growth without visible extravasation).

Class and exam questions

At what abdominal aortic aneurysm size is surgery indicated?

Intervention (open or EVAR) is indicated once the aneurysm diameter reaches 5.5 cm or more. Below this size, surgical risks outweigh the risk of rupture, so surveillance is maintained.

What is a type II endoleak and does it need immediate treatment?

This is blood leakage into the aneurysm sac from side branches (retrograde). In most cases, it is simply monitored and treated (embolized) only if the aneurysmal sac begins to enlarge.

What is the issue with the internal iliac artery in endovascular treatment?

It often has to be embolized to prevent a type II endoleak. However, unilateral embolization can lead to intermittent claudication of the gluteal muscles and erectile dysfunction.

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What else to study on this topic

Crawford classification of thoracoabdominal aortic aneurysms
Open surgical repair of aortic pathologies (OR)
Endovascular treatment of ruptured aortic aneurysm (rAAA) and the IMPROVE trial
Hybrid treatment methods for thoracoabdominal aneurysms
FEVAR strategy for a short conical aortic neck

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Endovascular interventions on the abdominal aorta