An arteriovenous malformation, or AVM, is an abnormal tangle of blood vessels in which arteries connect directly to veins without passing through the normal capillary network. This guide explains what AVMs are, where they can occur, and how physicians generally evaluate them—information intended to help patients and families understand this condition before speaking with a specialist.
What Exactly Is an AVM?
In a typical circulatory system, blood flows from arteries through progressively smaller vessels into capillaries, where oxygen and nutrients are exchanged with surrounding tissue, before returning to the heart through veins. In an AVM, this capillary network is missing or abnormal, so high-pressure arterial blood flows directly into veins that are not built to handle that pressure.
This direct connection—sometimes called a "nidus" when it involves a tangled cluster of vessels—can occur anywhere in the body, though AVMs in the brain and spinal cord receive particular clinical attention due to their potential complications. AVMs are generally considered congenital, meaning they are typically present from birth, though they may not be discovered until later in life.
What Are Common Symptoms of an AVM?
Many AVMs cause no symptoms and are discovered incidentally during imaging performed for an unrelated reason. When symptoms do occur, they vary widely depending on the AVM's location and size. Broadly discussed symptoms in the medical literature include headaches, seizures, and neurological symptoms for brain AVMs, or visible or palpable abnormalities for AVMs closer to the skin surface.
Because symptoms can overlap with many other conditions, a physician evaluation and diagnostic imaging are necessary to confirm an AVM diagnosis—this article does not describe symptoms specific to any individual's situation.
How Do Physicians Evaluate an AVM?
When an AVM is suspected, physicians typically use a combination of imaging studies to characterize its size, location, and vascular architecture, which may include:
- Magnetic resonance imaging (MRI): to visualize the AVM's relationship to surrounding tissue.
- Computed tomography angiography (CTA): to map the vascular anatomy.
- Catheter-based angiography: considered a detailed way to visualize arterial feeders, the nidus, and venous drainage patterns.
This evaluation helps the treating physician or specialist team understand the AVM's structure and discuss potential management options with the patient.
What Are General Management Considerations?
Management of an AVM is highly individualized and is determined by a physician or specialist team based on the AVM's location, size, symptoms, and the patient's overall health. Approaches discussed in clinical practice may include observation, embolization, surgical resection, radiation-based approaches, or a combination of these, depending on the specific case. All interventional approaches carry risks and benefits that should be discussed thoroughly with the treating physician.
Frequently Asked Questions
Are AVMs cancerous?
No, AVMs are vascular abnormalities, not tumors, and they are not cancerous. They involve abnormal connections between arteries and veins rather than uncontrolled cell growth.
Can an AVM go away on its own?
AVMs generally do not resolve without treatment, though their natural course varies by individual. Whether observation or active management is appropriate is a decision made by a physician based on the specific characteristics of the AVM.
Who should evaluate a suspected AVM?
A suspected AVM should be evaluated by a qualified physician, often in coordination with specialists in neurology, neurosurgery, or interventional radiology, depending on the AVM's location. Diagnostic imaging is typically required to confirm the diagnosis and guide any discussion of management options.
Related INVAMED Resources
- Embolization Products at INVAMED
- LIBRO Non-Adhesive Embolization Agent
- Request Information from INVAMED
Medical Disclaimer: This article is provided for general informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendation. It is not a substitute for consultation with a qualified healthcare professional. Product indications, availability, and regulatory status vary by country. Always refer to the official Instructions for Use (IFU) and consult a licensed physician for guidance specific to your situation. INVAMED devices are intended for use by trained healthcare professionals.