What are arteriovenous malformations?
Arteriovenous malformations (AVMs) are vascular birth defects that have the characteristic of having direct connections between arteries and veins. They are most frequently found in the brain, although they can be found anywhere in any organ. Arteriovenous malformations are typically congenital, meaning someone is born with it or experiences its development shortly after.
They can become a problem for multiple reasons. Most often the main problem is that they look ugly. However, they can also cause pain or result in bleeding complications. In some cases, they can cause increased blood return to the heart which can have long-term effects. In rare cases, especially when they happen in the kidneys or lungs, they could cause a stroke.
What are the symptoms of arteriovenous malformations?
The symptoms of peripheral AVM vary based on the size and number of shunts and the amount of tissue involved. In general, an AVM causes your tissue to enlarge because your arteries and veins expand and your affected tissue grows faster and larger than normal tissue. When there is an extremely large shunt, a peripheral AVM can cause heart failure which presents itself with shortness of breath or leg swelling.
Most AVMs get bigger over time. They often start out quietly and you may find that the skin over the AVM is reddish and warm. As the AVM progresses, your veinsexpand and the spot swells. If your peripheral AVM continues to progress, it can damage your tissue, causing pain, pressure sores, and ulcers, and possibly bleeding.
It is hard to predict how quickly AVM will progress. It often takes years before it does real damage. Hormonal changes during puberty or pregnancy, trauma or injury, and surgery can affect how quickly the AVM grows.
What are the types of Arteriovenous Malformations?
The arteriovenous malformations are classified depending on how many feeding arteries they have and the number of draining veins.
What is the treatment of AVMs?
Treatment for arteriovenous malformations depends on the location, complications, cause, and symptoms. Everything is individualized to each patient.
Treatment options include:
Surgery: if the primary options when the vascular malformation can be completely removed whithout causing too much damage. However, when the AVM involves organs, muscle or is near nerves or tendon, the surgery can cause more damage than good.
Embolization/Sclerotherapy: a procedure in which a material is injected in the abnormal vessels to block blood flow and essentially get rid of the vascular malformation with minimal damage to adjacent tissue.
What is the workup for arteriovenous malformations?
The work involves imaging studies including an ultrasound (which can be done in the office) and a CT scan or MRI scan. We want to make sure the diagnosis is correct and we have not mistaken a tumor for a vascular malformation.
In some cases, we may decide to do a diagnostic arteriogram to better evaluate the lesion. In this procedure, a small catheter is “snaked” through the groin or the wrist and we navigate it to the area of concern. Contrast dye is then injected and multiple pictures are taken. This is often the best way to evaluate the feeding vessels, draining veins, and how fast the flow is.
For all but the most simple AVMs, we then bring the patient back for staged treatment. In the interim, the patient’s history, physical exam findings, and MRI and angiographic images are reviewed by a team that includes interventional radiology and vascular surgery.
Complications of the Treatment
Postoperative pain and swelling should be expected and can sometimes be significant. Sometimes it may require pain medication, anti-inflammatories or steroids to decrease the inflammation.
Although rare, more serious complications involve skin necrosis/ulceration and nontargeted embolization which could cause compromise of the blood flow to other organs. Since every case is different, you need to discuss the specific risks in your case.
What is the follow-up after the procedure?
Patients are typically seen in the clinic once a month after treatment begins, sooner if indicated. We continue to see the patient until the symptoms are resolved.
What is the prognosis? Can vascular malformation be cure?
Outcomes vary considerably mostly due to the heterogeneous nature of AVMs. Large, diffuse AVMs are often not curable and embolization is merely palliative. Small AVMs, especially those with a single outflow vein, have a high chance of cure with embolization alone. However, if treated correctly, most patients will experience at least symptomatic improvement after endovascular therapy. Recurrence is a common problem, and in some cases, a repeat treatment can be required in the future.
What to expect when undergoing the procedure?
The procedure is done as an outpatient, which means you will go home on the same day. Most of the time the procedure is done with a local anesthetic and twilight anesthesia, but in some cases, general anesthesia is recommended. We do these procedures at El Camino Hospital in Mountain View, where we have all the equipment necessary for these types of procedures. The procedure is done in the Cath Lab, which is a specialized surgery room that has specialized imaging capabilities including fluoroscopy (Xrays), ultrasound, and CT.
Depending on the location or the type of the vascular malformation, a small tube is inserted in the groin, wrist, or directly into the malformation. We do not do any incisions or stitches.
After the procedure, you will be monitored for at least 2 hours to makes sure you are doing ok and there are no bleeding complications.