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Arteriovenous Malformations
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Blood Heart Circulation

Arteriovenous Malformations

Arteriovenous malformations (AVMs) are abnormal tangles of blood vessels that bypass capillaries, potentially leading to tissue damage and increased risk of hemorrhage.

Overview

Arteriovenous malformations (AVMs) are defects in the vascular system, which is the body's network of blood vessels. This system includes:

  • Arteries, which carry oxygen-rich blood from the heart to tissues and organs.
  • Veins, which carry blood and waste products back to the heart.
  • Capillaries, which are tiny blood vessels connecting small arteries to small veins.

An AVM is an abnormal tangle of arteries and veins connected directly to each other, with no capillaries in between. Without capillaries, blood flows from arteries directly into veins at a faster rate than normal. This rapid flow prevents nearby tissue from receiving adequate oxygen, which can lead to tissue damage and the death of nerve cells and other cells. Additionally, the fast rate of blood flow can increase blood pressure inside the arteries and veins, weakening them. A weakened artery or blood vessel could burst or leak blood.

Causes & Risk Factors

AVMs are rare, and the specific cause is unknown. Most people are born with them, but they can sometimes appear shortly after birth or later in life.

Symptoms

Symptoms depend on the location of the AVM. While they can occur anywhere in the body, they are more common in the brain or spinal cord. Most people with brain or spinal cord AVMs have few, if any, major symptoms. However, if a weakened blood vessel bursts, it can spill blood into the brain, a condition called a hemorrhage. Severe hemorrhages can cause a stroke and brain damage.

If an AVM is causing symptoms, they may include:

  • Seizures
  • Headache
  • Pain in the area where the AVM is located
  • Vision problems
  • Muscle weakness
  • Problems with movement and speech
  • Confusion
  • Dizziness
  • Loss of consciousness

Diagnosis

To determine if you have an AVM, a health care provider will typically:

  • Ask about your symptoms and medical history.
  • Perform a physical exam, which may include listening for a bruit. A bruit is a whooshing sound caused by rapid blood flow through the arteries and veins of an AVM.
  • Order imaging tests, such as a CT scan, MRI, ultrasound, or cerebral angiography. For a cerebral angiography, a special dye is injected to help blood vessels in the brain show up on x-rays.

Treatment & Management

Treatment options depend on several factors, including:

  • The location of the AVM
  • Its size
  • Your symptoms
  • Your overall health
  • Your risk of bleeding

Possible treatments include:

  • Monitoring for signs of an increased risk of hemorrhage.
  • Medicines to help manage symptoms associated with AVMs.
  • Surgery, which may be performed if there is a higher-than-usual risk of bleeding. There are various types of surgery for AVMs, and in some cases, more than one type may be required. Surgery can be risky, particularly when performed on the brain or spinal cord, so it is important to discuss the risks and benefits with a provider before making a decision.

Frequently Asked Questions

The three main treatment options are microsurgical resection, stereotactic radiosurgery, and endovascular embolization. The choice depends on the AVM's size, location, and the complexity of its blood vessels. Surgery is often considered for smaller, accessible AVMs to remove the tangle completely. Radiosurgery uses focused radiation to shrink the AVM over time and is suitable for smaller lesions in sensitive areas. Embolization involves injecting a substance to block blood flow and is often used alone for small AVMs or in combination with surgery or radiosurgery to reduce the size of larger ones before definitive treatment.
Not always. The decision to treat an asymptomatic AVM involves weighing the risk of treatment against the risk of the AVM bleeding. Some AVMs have a very low annual risk of hemorrhage, and the risks of surgery or radiation might outweigh the benefits of intervention. In such cases, doctors may recommend "watchful waiting" with regular MRI monitoring to ensure the AVM does not change. However, if the AVM is located in a high-risk area or has features that suggest a higher bleeding risk, proactive treatment may be recommended even without current symptoms.
Most people with AVMs can live normal lives, but those with untreated or partially treated AVMs are at risk for hemorrhage. While there is no definitive list of activities that cause AVMs to burst, doctors often advise avoiding activities that cause extreme spikes in blood pressure, such as heavy weightlifting, straining during bowel movements, or contact sports. Patients should also be cautious with medications that increase bleeding risk, such as aspirin or non-steroidal anti-inflammatory drugs (NSAIDs), unless approved by their neurologist. Managing stress and maintaining stable blood pressure are key to reducing the risk of complications.
Most AVMs are sporadic, meaning they occur randomly and are not inherited from parents. However, a small percentage of AVMs are associated with genetic conditions such as Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome. In HHT, AVMs can appear in multiple organs, including the lungs, liver, and brain, and the condition is passed down in an autosomal dominant pattern. If you have a family history of AVMs or frequent nosebleeds, genetic counseling and testing may be appropriate to determine if a hereditary cause is present.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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