Vascular Malformations

Vascular Malformations (VMs) are anomalies of development of the vascular tissue (arteries, capillaries and veins) of the body. These abnormal groups or collections of blood vessels are present at birth (though not always clinically evident) and grow proportionately with the child. VMs are rare but sometimes very debilitating diseases. The term vascular malformation encompasses a wide range of conditions with a confusing history of names and quite varied clinical presentation. Earlier treatments of these lesions were almost entirely surgical. Time and experience have revealed many limitations of surgery and shown the benefits of a variety of interventional radiologic techniques. Outlined below are the specific malformations and a description of some of the skills and techniques that interventional radiologists (interventionalists) are using to help improve the treatment and management of patients with these complicated conditions.

A variety of radiologic tests are now available to diagnose and characterize vascular malformations. Ultrasound (with color Doppler imaging) and magnetic resonance imaging (MRI) are two very useful tools in the work-up of these disorders. Arteriograms and/or venograms are also often necessary in evaluating these anomalies. These latter two techniques involve injections of contrast material that can be seen on X-ray pictures into arteries (arteriography) or veins (venography). Interventionalists use some combination of the above procedures to help diagnose the type of malformation and identify the type of blood flow present. Some VMs contain high, pulsatile blood flow while others exhibit very slow flow. Due to these different features some VMs require different forms of therapy than others.

Arteriovenous Malformations
Arteriovenous malformations (AVMs) are congenital anomalies that usually contain enlarged arteries that shunt blood through a network of abnormal, tortuous vessels into dilated veins. These lesions cause symptoms in the part of the body that they occupy. Some of these symptoms include skin ulceration, bleeding, and pain in the affected limb at rest or when it is used (claudication). The malformation may be disfiguring, possibly causing neurologic deficit of an extremity or region. Larger AVMs in the torso may have deleterious effects on the heart.

Under x-ray guidance, interventional radiologists can manipulate small steerable catheters into the abnormal arteries and veins and inject or place a variety of agents to occlude the blood flow, a procedure called embolization. Sometimes, small metal coils or tiny biologically inert particles (polyvinyl alcohol foam) are delivered to block the flow of blood. Other cases may call for different embolic agents such as ethanol (which causes clotting) or NBCA. NBCA, commonly referred to as "glue," is injected as a liquid and becomes solid inside the blood vessel. Arteriography or venography is performed as a part of these procedures to target the correct areas and monitor progress.

Arteriovenous Fistulae
Arteriovenous fistulae (AVF) are abnormal direct connections between arteries and veins. These lesions are marked by high flow of blood, similar to AVMs. While some AVF may remain clinically silent, others can produce swelling or pain. The high flow recruited by these anomalies can even deprive an affected extremity of its necessary blood supply. In such patients, significant cardiac effects may occur including heart failure.

A variety of agents and devices, including those described above, have been used to treat AVF. Again, treatment is performed as part of an angiographic procedure after the malformation has been fully evaluated.

Venous Malformations
Venous Malformations are abnormal dilated vascular structures that contain very slow flowing blood after it passes through a normal capillary bed. Like the other VMs above these can occur in a variety of locations. Small, asymptomatic venous malformations may require little treatment, whereas more problematic lesions can cause pain, skin ulceration or problems with blood clotting (coagulopathy). Such anomalies may need more aggressive therapy. Techniques described above are sometimes utilized to treat this type of VM, especially when it occurs in combination with an AVM or AVF. Frequently, these anomalies are amenable to direct puncture and can be sclerosed (fibrosed and occluded) with ethanol or another agent.

Initial Evaluation/Treatment
Prior to diagnostic or therapeutic procedures in interventional radiology, patients need to be fully evaluated. Evaluation can take place in our office at Riverside Methodist Hospital. It is very important to have a team of physicians from all relevant surgical and medical specialties who communicate together and take a cooperative approach to management of patients with these anomalies.

After initial clinical evaluation it is reasonable to expect that a diagnostic arteriogram or venogram may be scheduled. These tests are performed as an out-patient with sedation for adults and most adolescents. General anesthesia may be required in children and some adolescents. Patients usually return home the same day.

Interventional procedures to embolize VM are usually performed under general anesthesia since it is essential for the patient to remain completely still. These procedures may last a few hours or longer. After the embolization the patient is admitted to the hospital at least overnight and occasionally for a longer period of time. During admission, patients are usually treated with steroids (to decrease inflammation and pain), antibiotics and pain medication. After discharge, follow-up is scheduled through our clinic and as necessary with any other involved physicians.

Initial Evaluation/Treatment
Prior to diagnostic or therapeutic procedures in interventional radiology, patients need to be fully evaluated. Evaluation can take place in our office at Riverside Methodist Hospital. It is very important to have a team of physicians from all relevant surgical and medical specialties who communicate together and take a cooperative approach to management of patients with these anomalies.