Arteriovenous Malformations
What are they? | What do they look like? | How are they diagnosed? | What are possible complications? | How are they managed? | Hereditary Hemorrhagic Telangiectasia (HHT) | Contact us
What is an arteriovenous malformation?
An arteriovenous malformation is a localized or diffuse vascular lesion consisting of direct connections between arteries and veins, with the absence of the intervening capillary bed (network of tiny capillaries) that normally connects these vessels. Localized lesions, most commonly seen on the head and neck, often appear as light vascular stains at birth and generally do not enlarge until early childhood or adolescence. Diffuse lesions, commonly seen on the chest and abdomen or on a limb, may not be observed until later in childhood, as they enlarge with age. Both localized and diffuse lesions are seen in internal organs such as the brain, lung, liver, and bowel. Lesions within the brain are initially silent, with symptoms depending upon the rapidity of enlargement. Arteriovenous malformations are most common in the brain.
While the precise cause of arteriovenous malformations is unknown, they are thought to be caused by errors in the formation and development of the normal arterial-capillary-venous connections that occur very early in embryonic life; however, the differing growth patterns and microscopic presentations in localized as compared to diffuse lesions indicate other additional causes. There is no evidence that drugs or medications that may have been taken during pregnancy or environmental exposures that may have occurred during that time can cause arteriovenous malformations.
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What do arteriovenous malformations look like?
Due to differences in position, size, length, and number of arteriovenous malformations, there are wide variations in appearance. In many cases, there is no visible abnormality. However, when there is soft tissue involvement, these malformations generally show an overlying blush color in infancy and childhood. With age, the skin becomes a darker red or purple color and a firm mass appears beneath the stain. If you rest your hand over the lesion, you can sometimes feel pulsation of the blood as it rushes through the vessels.
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How are arteriovenous malformations diagnosed?
Physical examination reveals that the skin overlying the lesion is warm. Also, pulsation of blood flow can often be felt and an audible bruit (noise) can be heard with a stethoscope. Determining the location of the core of the lesion and the extent of the lesion is done through magnetic resonance imaging (MRI), magnetic resonance angiography (a specific type of MRI that looks at the flow of blood in vessels), or traditional angiography. These tests are essential both for diagnosis and treatment planning.
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What are the possible complications?
Intracranial (brain) lesions often cause headaches or other neurologic signs. They can also suddenly bleed into the brain. Lesions in other parts of the body may lead to ulceration, bleeding and persistent pain. If the blood flow through an arteriovenous malformation is excessive, the heart will enlarge over time, and this may result in a type of heart failure.
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How are arteriovenous malformations managed?
- Observation. Small asymptomatic lesions are sometimes just observed over time without intervention.
- Surgical excision (removal). This approach alone is more likely to be successful with localized lesions. When combined with preoperative embolization (injection of material into the center of the lesion to block the blood supply of the lesion, thereby reducing bleeding during surgery), it offers the best chance for cure. If the core of the lesion is completely removed, the lesion will not recur. When the location and extent of the arteriovenous malformation make removal of the entire core of the lesion impossible, the lesion may recur.
- Embolization. For more extensive lesions and/or when lesions are diffuse and surgery is not possible, embolization may improve overall quality of life by controlling the lesion and lessening the symptoms for a period of time.
- Some intracranial arteriovenous malformations are treated by protein-beam irradiation while others are treated with embolization or surgical care.
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Hereditary Hemorrhagic Telangiectasia (HHT)
A genetic disorder called hereditary hemorrhagic telangiectasia (HHT) or Rendu-Osler-Weber syndrome is characterized by multiple, small arteriovenous lesions that can occur in the skin, mucous membranes (mouth, nose, and gastrointestinal tract), lungs, liver, brain, and other sites. Two genes are known to cause this condition, both of which result in the dysfunction of cell receptors. In HHT, arteriovenous malformations usually present with telangiectasia (permanent widening of groups of superficial capillaries and tiny veins) of the skin and mucous membranes. Bleeding typically occurs during and after puberty, and treatment is aimed at minimizing bleeding. In cases of nosebleed, laser treatment of the nasal septum (thin membrane between nostrils) can be quite helpful.
Parkes-Weber Syndrome
Parkes-Weber syndrome involves diffuse arteriovenous malformations of a limb with overgrowth of the limb. These patients also may have lymphatic malformations. The affected limb usually has a capillary malformation involving skin. The heart may be affected secondary to increased blood flow in the involved area of the body. If untreated, this can result in an enlarged heart and eventually in heart failure.
MRI and magnetic resonance angiography (a specific type of MRI that looks at the flow of blood in vessels) are the most appropriate diagnostic techniques. Some patients also must undergo an echocardiogram to monitor the status of the heart.
Treatment may include embolization and, in some patients, surgical procedures.
Contact us
For additional information on this or any Health Topic, please call the Family Resource Center, 513-636-7606, or your pediatrician.
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Rev. 12/04, 05/07
