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Vascular Malformations


Vascular malformations are rare with some types found in less than 1 percent of the population. If you have one, chances are it developed before you were born. Many types of vascular malformations don’t cause symptoms until they are triggered by such events as adolescence, pregnancy, or some major surgery, trauma or injury.

Vascular malformations are a result of the abnormal growth and development of a single type of vessel or a combination of vessels. Over the years, malformations can grow larger and become problematic depending on what type(s) of vessel is involved. They can be harmless and minor or very serious, sometimes even life-threatening.

Until recently, medical experts had an insufficient and sometimes haphazard lexicon to describe vascular anomalies, and that resulted in poor communication among doctors and patients alike. While this has largely changed, many people still visit multiple doctors as they seek an accurate diagnosis.

“Most of our patients have received confusing or conflicting information regarding their condition,” says Naiem Nassiri, MD, a Yale Medicine vascular surgeon and a co-director of the Vascular Anomalies & Malformation Program (VAMP) at Yale Medicine. While there is no complete cure for vascular malformations, the program pulls in a diverse, highly experienced team of specialists who work together to determine the most appropriate diagnosis and treatment plan for each patient.

What is a vascular malformation?

A vascular malformation is an abnormal development of blood vessels. They might be found in the large arteries and veins, in smaller vessels called arterioles and venules, in microscopic capillaries, and/or in the lymphatic channels that carry lymphatic fluid and white blood cells outside of the arteries and veins. 

How is a vascular malformation diagnosed?

After a thorough history and physical exam, the doctor’s first step is to determine whether the abnormality is, in fact, a vascular malformation, and not another type of vascular abnormality such as a hemangioma. This is a benign tumor or noncancerous growth of the blood vessels.  A person can have a single isolated vascular malformation or one that involves several vessels. In some cases, a vascular malformation turns out to be part of a more complex syndrome that features multiple disorders and affects multiple organs. 

Typically, doctors will order imaging studies to help with diagnosis. Imaging studies may include ultrasound, MRI, and/or angiography, an imaging procedure that involves the injection of dye that will outline the blood vessels on an X-ray.

What are the different types of vascular malformations?

Vascular malformations are most easily categorized based on the type(s) of vessels involved and how blood flows through them. They include the following:

  • Capillary malformations, also known as port-wine stains
  • Slow-flow venous and lymphatic malformations
  • Fast-flow arteriovenous malformations (AVMs) and arteriovenous fistulas (AVF)
  • Congenital mixed syndromes such as Klippel-Trenaunay Syndrome

What are some characteristics of capillary vascular malformations?

Slow-flow vascular malformations include venous and lymphatic malformations.

Venous malformations: These are the most common vascular malformations. They affect the veins, which carry blood from organs back into the heart and lungs for re-oxygenation. They can occur anywhere in the body, and they can be isolated or part of a syndrome, most commonly Klippel-Trenaunay Syndrome.

These venous malformations tend to be identified later in life; typically, symptoms are triggered by an injury, or physiological changes such as puberty or pregnancy. Sometimes they are found incidentally, during MRI studies for other conditions. Symptoms suggesting a possible venous malformation range from minor aches and pains to recurrent bouts of bleeding, clotting disorders and organ damage, mostly within bones, joints and skeletal muscles.

Lymphatic Malformations: The lymphatic vessels carry lymphatic fluid and white blood cells outside of the arteries and veins. Malformations affecting the lymphatic channels may start to cause problems during infancy and early childhood. They can cause pooling of the lymph fluid into cysts or fluid-filled pockets of various sizes. These cysts, in turn, can develop problems such as infection, bleeding and erosion into adjacent organs.

What are some characteristics of fast-flow arteriovenous malformations?

Fast-flow arteriovenous malformations develop as the result of an abnormal connection between arteries that supply the body’s organs, and the veins, which drain them. Picture these as being like short-circuits: Blood pumped from the heart to a given organ can’t get there and is instead sent back toward the heart. The draining veins become dilated and engorged, the target organ is deprived of needed oxygen and nutrients, and–in the worst scenarios—heart and/or organ failure can develop.

Arteriovenous malformations can occur anywhere in the body, but are most typically found in the brain, spinal cord and extremities. It is rare, but possible, for arteriovenous malformations to be found in the internal organs, including the kidneys, the intestines and the lungs. While there is currently no cure for arteriovenous malformations, various treatment options exist aimed at slowing their growth, and minimizing and at times eliminating symptoms. 

What are the congenital mixed vascular malformation syndromes?

There are several congenital mixed syndromes that involve vascular malformations.

Klippel-Trenaunay Syndrome (KTS): This syndrome is diagnosed if two the following three criteria are present: port-wine stains, bony and/or soft tissue overgrowth, slow-flow venous/lymphatic malformations. The venous malformations in KTS can be quite extensive and involve bones, joints and muscles, as well as the skin and the underlying fat. There is an increased risk of recurrent infections, as well as clotting in the veins.

Parkes-Weber Syndrome: This is very similar to Klippel-Trenaunay Syndrome, except that it involves high-flow arteriovenous malformations associated with an arm or leg.

Blue Rubber Bleb Nevus Syndrome: Also known as Bean Syndrome, this refers to the presence of multiple, isolated slow-flow venous malformations on the skin and in underlying tissue, as well as in the intestines and other internal organs.

CLOVES (congenital lipomatous overgrowth, vascular malformations, epidermal nevi and spine deformities): This condition, which affects infants and young children, features fatty tissue overgrowth throughout the body. It commonly affects the trunk, feet and limbs, head or neck. Some children have a deep red (purplish) rash that looks something like a port-wine stain. People with CLOVES may have spinal deformities such as scoliosis and high-flow arteriovenous malformations that affect the spinal cord.

Hereditary Hemorrhagic Telangiectasias (HHT): Also known as Osler-Webe-Rendu Syndrome, this condition (passed by parents to children) is marked by malformations of small-end arteries. The symptoms include multiple nosebleeds and skin rashes, particularly on the palms of the hands and feet. Getting proper treatment is vital to prevent clots from traveling to the brain. 

How are vascular malformations treated?

Treatment varies, depending on the type of blood vessel that is involved, the type of vascular malformation or syndrome, and the overall health of the patient. Since there is no cure for most vascular malformations, treatment aims to minimize symptoms. Having input from different kinds of specialists, each with unique sets of skills and experience, helps identify what’s best for each patient.

Treatment options can range from addressing minor (cosmetic) concerns to providing life-saving care for critical conditions. They may include one or more of the following approaches:

  • Catheter-based techniques such as embolization, a procedure to close off a problematic blood vessel; and sclerotherapy, the injection of a chemical to cause a vessel to close
  • Laser therapy
  • Simple observation with regular follow-up visits
  • Surgery, sometimes followed by reconstruction, which may be used in conjunction with other treatments. If there are widespread, deep lesions, multiple treatments are often necessary. 

Can a vascular malformation recur?

Unfortunately, vascular malformations can come back. While there are many options for managing symptoms, these problems can recur even after successful treatment. For this reason, it’s important to schedule regular follow-up visits with a specialist to minimize recurrent symptoms and associated complications.

How is Yale Medicine unique in its care of vascular malformations?

Yale Medicine’s VAMP is one of only a handful of programs in the country that provide highly specialized, collaborative care for vascular malformations. We are a prominent national and international referral center for management of all vascular anomalies, including vascular malformations, as well as hemangiomas. 

Treating vascular malformations calls for a diverse team of specialists. The VAMP team includes dermatologists, radiologists, and plastic and vascular surgeons who meet regularly to review each patient’s case individually. They discuss all of the available options, and consider all of the risks and benefits before determining the safest, most appropriate treatment plan.

In addition, we provide our patients with comprehensive, state-of-the-art, integrated diagnostic and therapeutic services in one location.