Use of ethylene-vinyl alcohol copolymer as a liquid embolic agent to treat a peripheral arteriovenous malformation in a dog

Abstract

Case Description An 11-year-old castrated male Tibetan Mastiff was evaluated because of a visibly enlarged blood vessel and progressively worsening swelling of the right hind limb. Clinical Findings On physical examination, the right hind limb was markedly larger than the left hind limb and the dog was minimally weight bearing on the affected limb. A bruit was auscultated over the affected region. Ultrasonography of the tarsal region of the right hind limb revealed an artery with turbulent flow that communicated with venous drainage. A CT scan confirmed the presence of an arteriovenous malformation (AVM). Treatment and Outcome Embolization of the AVM with a liquid embolic agent (ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide) was elected. An arteriogram was performed prior to treatment and delineated the vessels that were targeted for embolization. The embolic agent was infused into the AVM, and a postinjection arteriogram confirmed complete occlusion of the AVM nidus and normal arterial flow to the paw with subsequent normal venous drainage. The circumference of the abnormal paw was 51 cm before the procedure and 22.9 cm at 4 weeks after the procedure. Additionally, the gait of the dog dramatically improved. No complications associated with the procedure developed. Clinical Relevance Peripheral AVMs in dogs are uncommon, and described treatment options are limited and generally associated with serious morbidity. A liquid embolic agent, ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide, was successfully administered in this case, and no morbidity was observed secondary to the procedure. Clinical success was characterized by substantial improvement in limb swelling and marked improvement in the gait of the dog.

Angiographic Anatomy of the Major Abdominal Arterial Blood Supply in the Dog

“…The iliac arteries may be selected during the treatment of vascular anomalies or for the delivery of intraarterial chemotherapy or embolization. There is a previously published description of a distal pelvic limb vascular anomaly in a dog in which an embolization procedure was performed. For that case, the femoral artery was the vascular access point.…”

Imaging Diagnosis—radiographic, Ultrasonographic, Computed Tomographic, and Fluoroscopic Appearance of a Distal Pelvic Limb Arteriovenous Malformation in a Young German Shepherd Dog

“…Arteriovenous fistulas and AVMs have been defined as abnormal communications between arteries and veins that bypass the normal capillary bed . These have been described in the musculature, liver, lung, and heart . The nomenclature of vascular anomalies has been confusing in both human and veterinary medicine, due to the utilization of several classification systems .…”

“…Reported treatment approaches for AVF and AVM of veterinary patients have included surgical ligation or excision, coil embolization, and percutaneous cyanoacrylate embolization . In people, ethanol embolization of peripheral AVMs involving the bone can be done by direct puncture or by a transarterial approach.…”

“…4,5 The nomenclature of vascular anomalies has been confusing in both human and veterinary medicine, due to the utilization of several classification systems. 3,5 In general, the term AVF has been used to describe a lesion characterized by a single connection between an artery and vein. The term AVM has been used for more complex lesions that involve multiple aberrant shunting vessels that originate from one or more arteries and terminate in one or more venous structures.…”

Congenital subcutaneous arteriovenous malformation in a puppy: diagnosis with CT angiography

“…Treatment options vary depending upon the location and dimension of the lesion . Ligation of an AV fistula may be difficult because of extensive local vascular proliferation.…”