Intervention planning: anatomical nuances
Precise anatomical evaluation is critical for successful stent-graft placement. The primary imaging method of choice is CT (computed tomography), which provides high detail.
Evaluation of the aneurysm neck and renal arteries:
- The distance from the neck to the inferior renal artery must be $\ge$ 15 mm.
- A conical neck shape, pronounced atheromatosis, and angulation greater than 60° can impair sealing and lead to endoleaks or device migration.
- If the stent covers accessory renal arteries, differential renal function must be assessed in advance.
Evaluation of the iliac and femoral arteries: Diameter, tortuosity, and the presence of stenoses that hinder stent-graft delivery are examined. In iliac artery aneurysm, embolization of the internal iliac artery may be required, which carries the risk of buttock claudication.
Features of aortic dissection management
Aortic dissection requires a specific approach depending on the Stanford classification type.
- Type A dissection (involves the ascending aorta/arch): requires immediate open surgery due to staggering mortality.
- Type B dissection (descending aorta only): uncomplicated cases are managed medically. Surgical/endovascular intervention is indicated if medical therapy fails, complications develop, or in patients with Marfan syndrome.
When planning stenting, it is important to determine whether the visceral branches originate from the true lumen or false lumen. Stent-graft placement covers the primary entry tear, expands the true lumen, and promotes thrombosis of the false lumen, resolving branch ischemia.
Traumatic aortic injury (TAI)
Modern management of TAI (Traumatic Aortic Injury) involves delayed treatment to stabilize the patient. Controlled hypotension ($\beta$-blockers and vasodilators) is mandatory to maintain a mean arterial pressure of less than 70 mm Hg.
Endovascular stenting has become the preferred method, significantly reducing mortality. The most common site of injury is the aortic isthmus. Due to its proximity to the left subclavian artery (LSA), the proximal landing zone is often insufficient. In such cases, the ostium of the LSA is intentionally covered (overstenting). The risk of acute arm ischemia in this case is low, but the probability of central neurological complications is about 10%.
Postoperative follow-up and complications
Patients require lifelong monitoring. The most common complication is endoleaks (periprosthetic leaks).
- CT is the gold standard for visualizing stent material and detecting endoleaks (e.g., dangerous type I endoleaks at the proximal neck or type III in case of component disconnection).
- MRI (with time-resolved MR angiography) effectively visualizes endoleaks, but metal artifacts may obscure small defects or stent fractures.
- CEUS (contrast-enhanced ultrasound) is a promising method to reduce radiation exposure during follow-up.
Briefly: answers to topical questions
What are the types of endoleaks following endovascular aortic repair?
Endoleaks are classified into 5 types.
- Type I — secondary leak due to inadequate sealing at the stent-graft fixation site, occurs in less than 10% of cases, usually requires treatment
- Type II — retrograde filling of the aneurysmal sac via collateral branches (lumbar, inferior mesenteric, or internal iliac arteries), up to 25% of cases
- Type III — mechanical damage to the graft or separation of modular components
- Type IV — secondary leak due to graft material porosity, almost always resolves spontaneously
- Type V — endotension, sac expansion without visible abnormalities on CT angiography
What are the absolute contraindications to endovascular treatment of thoracic aortic diseases (TEVAR)?
Absolute contraindications include a number of clinical and anatomical factors.
- Lack of patient consent (lack of patient consent)
- Limited life expectancy — if the risks of the intervention outweigh the potential benefits
- Low cardiopulmonary reserve or other comorbidities — if risks outweigh benefits
- Unstable patients — condition does not allow withstanding the delay for imaging the pathology
- Ascending aortic pathology — except for cases with no surgical alternative
Rupture, malignancies, and mycotic aneurysms are not contraindications.
Which aortic arch branches, besides the left subclavian, may require coverage or debranching during TEVAR?
In addition to the left subclavian artery, sources cite the following as aortic arch branches:
- Brachiocephalic artery (brachiocephalic artery) — the first branch of the aortic arch
- Left common carotid artery (left common carotid artery) — the second branch of the aortic arch
For aortic arch pathologies, sources describe rerouting (debranching) of the major arch vessels followed by transcatheter isolation of the pathology. For interventions in zones 1 and 2 of the aortic arch, a combined hybrid aortic arch procedure with transcatheter pathology isolation is used.
What complications are caused by internal iliac artery embolization during endografting?
Embolization of the internal iliac artery (IIA) causes pelvic ischemic complications.
- Buttock claudication (buttock claudication) — up to 31% of cases with unilateral embolization
- Erectile dysfunction — up to 17% of cases with unilateral embolization
With bilateral embolization, risks are higher. A modern solution to preserve gluteal perfusion is iliac-branched devices, which maintain IIA patency.
Class and exam questions
Why is a stent-graft not deployed in type A dissection?
In type A dissection, the risk of retrograde propagation of the dissection into the ascending aorta and fatal complications (tamponade, coronary artery involvement) is extremely high, therefore emergency open surgery is required.
What is a type I endoleak and why is it dangerous?
A type I endoleak is blood leakage between the aortic wall and the edge of the stent-graft (often due to poor sealing or migration). This is the most dangerous type of endoleak, requiring re-intervention.
Why are beta-blockers necessary in aortic trauma?
They reduce the rate of rise of left ventricular systolic output, decreasing shearing force on the damaged aortic wall.
What else to study on this topic
- Features of the differential diagnosis of inflammatory aortitis and acute intramural hematoma on MRI.
- The use of branched and fenestrated stent-grafts in thoracoabdominal aneurysms.
- Middle aortic syndrome: clinical presentation and the role of imaging.
- Detailed classification of endoleaks and management for each type.
- Percutaneous fenestration of the intimal flap in aortic dissection.
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