Subclassification and Treatment Results of Ethanol Embolotherapy of Type II Arteriovenous Malformations of the Extremity and Body
How safe and efficacious is ethanol and coil embolization of type II arteriovenous malformations (AVM) using a new subtype classification?
Embolization of type II AVMs using ethanol and coils within the framework of the new subtype classification described is safe and efficacious. Additionally, there is a higher cure rate for type IIa AVMs compared to type IIc AVMs.
Ko, Seong Eun et al. Subclassification and Treatment Results of Ethanol Embolotherapy of Type II Arteriovenous Malformations of the Extremity and Body. Journal of Vascular and Interventional Radiology, Volume 30, Issue 9, 1443 - 1451
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SummaryRecognizing that the treatment strategy of type II AVMs differs according to variations in the draining veins, the authors of this retrospective review propose a new subtype classification of type II AVMs according to the morphology of the draining vein.
A total of 316 patients with congenital body and extremity AVMs were included in the study. After performing arteriography to define morphology and flow dynamics, AVMs were treated with a combination of coils and ethanol. Coils were utilized to reduce the flow velocity within the venous segment, followed by ethanol to obliterate the residual fistulae. For type IIa AVMs (shunts between multiple arterioles and a focal segment of the draining vein) the venous segment was accessed via direct puncture or transvenous cannulation followed by embolization with coils. Once slow flow was seen within the AVM post coil embolization, high-concentration ethanol was injected through a transarterial microcatheter or through the percutaneous needle or transvenous catheter to complete embolization. For type IIb AVMs (multiple shunts between multiple arterioles and a venous sac), the venous sac was punctured, embolized with coils, and ethanol then injected through the needle or transarterial microcatheter. For type IIc AVMs (shunts between multiple arterioles and a long segment of draining vein), direct puncture or transvenous cannulation was performed for coil embolization with ethanol injection performed between deployment of multiple coils. The median clinical follow-up period was 12 months among 75 patients.
The overall treatment outcomes of ethanol embolotherapy with or without coils were cure in 70 lesions (83%), marked improvement in 6 lesions (7%), improvement in 5 lesions (6%), no change in 1 lesion, and treatment failure or aggravation in 2 lesions (2%). Among AVM subtypes, the cure rate was highest in type IIa AVMs (37 of 39; 95%), followed by types IIb (19 of 25; 76%) and IIc (13 of 20; 65%). There were 19 (10%) minor and 6 (3%) major complications (total of 189 treatment sessions). The complication rate was not significantly different among the subtypes of type II AVMs (P >.05). Major complications included compartment syndrome, acute pancreatitis, arm amputation due to infection, massive hematuria, and lymphedema. There was no mortality related to embolotherapy.
Various sclerotic agents and methods for embolization of type II body and limb AVMs have been described in the literature. The authors have demonstrated that ethanol, which may be the preferred embolic agent for such AVMs due its strong devascularization effect, can be used with similar efficacy and less risk of complication compared to methods already described by reducing shunt volume by means of coil embolization of the draining vein and allowing for use of a smaller volume of ethanol. Therefore, understanding the drainage pattern of these AVMs is important and the alternative subtype classification described here for body and limb AVMs will provide an additional framework for how we think about-and approach-these complex vascular lesions.
Zagum Bhatti, MD
Department of Radiology, Interventional Radiology Division
University of Texas Health Science Center at Houston, Houston, TX