Arteriovenous Malformation (AVM)
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In addition, AVM treatment and management routinely require the close collaboration of other specialists, including diagnostic radiologists, wound experts, and vascular, orthopedic and plastic surgeons who could care for AVM patients for life. Houston Methodist offers expertise in all of these specialties.
An arteriovenous malformation (AVM) is a rare disorder present at birth. It is a mass of knotted, abnormally formed arteries and veins that create a kind of circulatory short cut, which causes intense pressure because of rapid blood flow in the veins. AVMs can become disfiguring, life-threatening and develop anywhere in the body, especially in a patient’s limbs or trunk. They can rupture, burst through skin and bleed.
To understand AVMs, try to think of the lymphatic system (part of the circulatory system) as made up of small vessels that carry all of the fluid that escapes from the arteries, capillaries and veins back into circulation. AVMs can arise from all of these components. They can consist of one component (just veins) or can be mixed (arteries and veins); some involve deep structures, others only the skin. Moreover, they can grow to any size
It’s unclear what causes AVMs. Thought to be present at birth, growth may occur at different stages in life. Experts believe dormant AVMs can be triggered by a hormone response such as puberty or pregnancy. AVMs have also been noticed after local trauma, although this may be because the injury has drawn attention to the lesion. Growth in other AVMs appears to occur sporadically. Still others appear to be associated with other medical conditions.
How an AVM is diagnosed depends on the patient’s symptoms, which in turn depend on the AVMs location. In addition to taking a patient’s history and performing a physical exam, the doctor will ask about additional medical conditions, which may be associated with the disease.
The physical exam also will provide information on the type and extent of the AVM, especially for extremity malformations. Deeper AVMS and those on the trunk are much more difficult to diagnose.
Some form of non-invasive imaging (CT or MRI scan) is required to determine the type and extent of the AVM, if it involves any vital structures, if it can be removed surgically and if it affects adjacent tissues. At Houston Methodist, leading imaging specialists use world-class dynamic magnetic resonance venography, or MRV, and image fusion to develop an incredible, specific picture of the AVM.
Generally, AVMS are not curable, but they can be controlled. Some don’t require any therapy other than reassurance; others, like limb venous malformations, require minimal treatment, such as compression stockings. Though some AVMs may be removed surgically, this is not an option in the majority of cases due to the AVM’s location, size and involvement of adjacent structures.
When possible, our specialists use highly sophisticated approaches in their treatment of AVMs, including robotic catheters, direct puncture and sclerofoam.
Most AVMs are best treated with a minimally invasive technique called embolotherapy, during which a kind of glue is injected via a catheter into the AVM to block blood flow into it. Houston Methodist specialists use Onyx®, described as a lava-like substance, embolization glue, absolute alcohol and embolization coils (for large AVMs) to stop blood flow. Typically, especially for large AVMs, patients will require multiple embolization treatments, some even years later.
Sclerotherapy can be performed if the AVM is strictly involved in the veins. Doctors inject a solution into the vein, causing it to scar and collapse. The procedure forces blood to detour through healthier veins. Specialists might have to perform these procedures to control recurring AVMs.
Following an AVM procedure, patients can expect to stay at least one night in the hospital, with minimal discomfort for one to three days. With direct injection into an AVM, there is often some inflammation and swelling, which can be controlled with painkillers and anti-inflammatory medications.