AVM Embolization

Background and indications

Arteriovenous malformations (AVMs) are congenital high-flow vascular anomalies characterized by abnormal direct connections between arteries and veins (nidus), without capillary bed interposition. They can be located in the brain, spinal cord, lungs, liver, extremities, or head and neck. Endovascular embolization is the first-line treatment in most locations, aiming to occlude the nidus to eliminate the arteriovenous shunt.

Embolization indications include: symptomatic AVMs (hemorrhage, pain, high-output heart failure, skin ulceration), progressive AVMs (Schobinger classification), and pulmonary AVMs (risk of paradoxical embolism and stroke).

Pre-procedure assessment

Assessment includes MRI (characterization, extent, anatomic relationships), MR or CT angiography (vascular architecture), and possibly diagnostic arteriography. Schobinger classification (stages I-IV) guides treatment indication. Pulmonary AVMs are systematically screened in hereditary hemorrhagic telangiectasia (HHT) patients.

Procedure

Under general anesthesia, a catheter is introduced through the femoral artery. Under fluoroscopic guidance, feeding arterial pedicles are selectively catheterized to the nidus. Embolization agents include: acrylic glue (Glubran/Histoacryl) for high-flow nidus, Onyx (ethylene vinyl alcohol copolymer) for controlled nidus penetration, or coils for large-caliber pedicles. For pulmonary AVMs, vascular plugs (Amplatzer) or coils occlude the afferent artery. Multiple sessions 4-8 weeks apart are often needed.

Results and scientific evidence

For pulmonary AVMs, embolization offers 95-99% technical success rate and significantly reduces stroke and brain abscess risk in HHT patients (Faughnan et al., Annals of the American Thoracic Society, 2020; DOI: 10.1513/AnnalsATS.201909-652CME). For peripheral AVMs (extremities, face), embolization stabilizes or improves symptoms in 70-85% of cases, though complete cure is rare for extensive AVMs (Do et al., Journal of Vascular Surgery, 2012; DOI: 10.1016/j.jvs.2012.05.077).

Risks and complications

Risks vary by location: non-target embolization (2-5%), skin necrosis (5-10% for superficial AVMs), local pain (30-50%), nerve injury (< 2%). For cerebral AVMs, peri-procedural stroke risk is 3-5%. Paradoxical progression may occur after partial embolization.

Recovery

1-3 night hospitalization depending on location and extent. Follow-up by MRI/MRA at 3 and 6 months. Multiple embolization sessions are often needed.

Practical information

The procedure is performed as a short inpatient stay. It is performed by an interventional radiologist specialized in vascular malformations, ideally at a multidisciplinary reference center.