Arteriovenous malformations are a type of vascular malformation treated in our Vascular Anomalies Center at Children's Hospital Los Angeles.
Arteriovenous malformations (AVM) are fast-flow vascular lesions consisting of excess arteries connected directly to enlarged veins. The intervening tiny vascular architecture, or capillary network, is abnormal or absent. AVMs are most common in the head and neck, followed in frequency by the limbs, trunk, and internal organs. Frequently, AVMs occur in the brain, causing headaches or other neurologic signs or with sudden intracranial bleeding.
Arteriovenous fistulas (abnormal connections between arteries and veins) are frequently present. The result is a pulsatile mass. AVMs are present at birth, but often do not appear until infancy or later. There is no known cause of AVMs. Some occur in a familial disorder called hereditary hemorrhagic telangiectasia or Rendu-Osler-Weber syndrome.
Diagnosis for Arteriovenous Malformations
Diagnosis can be made on physical examination. An AVM is warm and not compressible like a venous malformation. It also has a notable pulse. Magnetic resonance imaging (MRI) is effective in confirming the diagnosis and developing treatment options. Other studies such as ultrasonography or angiography may detect the extent of AVMs.
Arteriovenous Malformations Over Time
The appearance of an AVM is sometimes mistaken for a hemangioma or "port-wine stain.” The "hormonal spurt" of puberty may play a role in the growth of AVMs. Trauma to the area also seems to trigger accelerated expansion of these lesions. In these situations, the skin becomes deep red or purple and warm to the touch. A mass may appear and a pulsation can often be felt. It can also be detected as a “bruit” (whooshing noise) with a stethoscope.
Treatment for Arteriovenous Malformations
As with other vascular malformations, surgical excision of an AVM, when possible, gives the best chance for a “cure.” However, this is often difficult and not without risk. For intracranial AVMs, proton-beam irradiation may be used. Generally, treatment is considered when signs of pain, non-healing skin ulcerations, bleeding, or increased cardiac output occur. Frequently, embolization (occlusion of the feeding vessels to the AVM) of the lesion is done to temporarily occlude blood-flow prior to surgical excision. Embolization alone may treat some of the symptoms of AVMs, but it is usually not “curative.” It should be noted that any intervention may trigger expansion of these lesions. The mechanism for this phenomenon is unknown.
Complications of Arteriovenous Malformations
Acute bleeding, pain, tissue loss, or ulceration may occur. If a wound becomes extensive, heavy bleeding may occur, and it is important to be ready to visit an emergency room. AVMs in the head may cause headaches, seizures, or can suddenly bleed.