Venous Malformations

Abstract

Vascular malformations are errors in vasculogenesis with the particular characteristics of the lesion determined by the vessel in the vascular system that is involved. As a result, these malformations can include arteries, veins, lymphatic vessels, or capillaries. Hemangiomas are NOT arteriovenous malformations (AVMs), and vice versa. Low-flow venous malformations are the most common form of vascular malformation—simplified, they are a number of tortuous vascular channels. Arteriovenous fistulas (AVFs) are an abnormal connection between an artery and a vein. Although these high-flow lesions can be congenital, often they are acquired as the result of surgery, penetrating trauma, or erosion by adjacent disease processes. The Yakes' classification is a relatively new system that characterizes AVMs based on their angioarchitectures suggesting possible treatment strategies. Treatment of venous malformations has improved over the past decade as a result of advances in percutaneous and transcatheter embolotherapy and sclerotherapy. Preprocedure evaluation of a malformation with either ultrasound or MRI is helpful not only in defining the extent of the abnormality but also in aiding to determine possible direct access into the lesion. Venous malformations may have a number of large-diameter connections to the deep venous system. It is important to control the injection to prevent the liquid embolics from entering these central veins.