ABSTRACT
An arteriovenous fistula is an abnormal connection between an artery and a vein. As a consequence, the blood bypasses the capillary bed. The majority of arteriovenous malformations (AVMs) are congenital, but some can be acquired due to trauma, infection, or malignancy. Vascular malformations are divided into low- and high-flow lesions. Low-flow malformations are venous, lymphatic, or mixed and therefore cause congestion of either type. Pelvic AVMs may produce pain, pelvic venous congestion, sexual dysfunction, and, occasionally, high-output cardiac failure and hemorrhage. With respect to hemorrhage, this is generally a lower gastrointestinal bleed or hematuria, while hemorrhage in the abdominal cavity is extremely rare. The mainstay of treatment of high-flow AVMs is permanently closing or eliminating the vascular nidus where arterial blood is shunted to the veins. Embolization of the nidus of an AVM often requires super-selective catheterization of numerous arterial feeding branches. This is facilitated by use of coaxial microcatheter systems.
