Congenital Arterial Malformation

Congenital arterial malformation is an abnormal tangle of blood vessels present at birth, where arteries connect directly to veins without the normal capillaries in between. This rare condition can occur anywhere in the body and may cause serious complications including bleeding, tissue damage, and strain on the heart.

Table of contents

• What is a congenital arterial malformation?
• Types of vascular malformations
• What causes these malformations?
• Signs and symptoms
• How are they diagnosed?
• Treatment options
• Living with the condition

What is a congenital arterial malformation?

A congenital arterial malformation, often called an arteriovenous malformation or AVM, is an abnormal tangle of blood vessels that looks like a bird’s nest^[1][6]. This condition is usually present at birth, which is why it is called “congenital”^[4][8].

In a healthy body, blood moves in an organized way. Arteries carry oxygen-rich blood from the heart to the body’s organs and tissues. This blood then passes through tiny vessels called capillaries, where oxygen and nutrients are delivered to cells. Veins then return the oxygen-poor blood back to the heart and lungs^[1][6].

When someone has an AVM, the bridge of capillaries between arteries and veins is missing. Blood flows directly from high-pressure arteries into veins that are not built to handle such strong blood flow^[1][6]. This creates a shortcut where blood returns to the heart without delivering oxygen to the body’s tissues. The heart must work harder than normal to compensate, and the abnormal connection can cause blood vessels to rupture and bleed^[1][6].

Congenital vascular malformations occur in about 1 percent of all births^[4][8]. They are rare conditions that can vary from simple, flat birthmarks to complex structures deep within the body^[4].

• Brain
• Spinal cord
• Arms and legs
• Face
• Lungs
• Liver
• Heart
• Stomach and intestines
• Hands and feet

Types of vascular malformations

Vascular malformations are named according to which type of blood vessel is mainly affected^[3][8]. The main types include:

Arteriovenous malformations (AVMs) are the most serious type. They occur when there are abnormal direct connections between arteries and veins. AVMs most commonly occur in the brain, brainstem, and spinal cord, but can develop anywhere in the body^[1][6]. These can lead to high blood flow, significant pain, bleeding, and strain on the heart^[15].

Venous malformations are the most common type and occur entirely in the veins. They may appear as thin-walled areas where blood collects, sometimes developing in grape-like clusters^[8][12].

Lymphatic malformations can cause swollen or enlarged lymph vessels that look like tiny water balloons underneath the skin^[15].

Capillary vascular malformations, also called port-wine stains, affect very small blood vessels underneath the skin and appear as patches of pink or purple skin^[3][15].

Some malformations can involve combinations of different types of blood vessels^[3][4].

What causes these malformations?

Scientists are not completely sure what causes congenital arterial malformations. In most cases, children are born with them, and they likely develop during fetal development (growth in the womb)^[6][10].

Some AVMs are caused by genetic changes (called mutations or variants) that happen early in pregnancy. The mutation starts in one cell, and any cells that divide from that cell continue the mutation. This is called a mosaic mutation. The abnormal gene is not passed down by parents^[7].

In rare cases, AVMs may be hereditary, meaning they run in families^[6][10]. They can be associated with certain genetic syndromes, including:

• Parkes-Weber syndrome, which causes multiple AVMs in one arm or leg^[7]
• Hereditary hemorrhagic telangiectasia (HHT), which causes AVMs in the lungs, brain, and digestive tract^[7]
• Cobb syndrome, which involves vascular malformations of the skin and AVMs in the spine^[23]
• Wyburn-Mason syndrome, which involves AVMs of the retina and brain^[23]

Signs and symptoms

Many people with arteriovenous malformations experience few or no significant symptoms. In most cases, AVMs are discovered only by accident, usually during treatment for an unrelated condition^[1]. Some people have no symptoms at all—up to 15 percent of people with AVMs^[6].

However, when symptoms do occur, they can be serious. About 50 percent of people with a brain AVM first discover they have it when bleeding occurs^[6]. Many AVMs are not noticed until later in life, although some can be seen in newborns^[7].

Symptoms depend on where the AVM is located in the body:

Brain AVMs may cause seizures with or without loss of consciousness, persistent headaches, muscle weakness or paralysis on one side of the body, problems with speaking, loss of coordination, numbness or tingling, dizziness, problems with movement or vision, and mental confusion^[1][6].

Spinal cord AVMs can cause sudden and severe back pain or weakness in the lower body and legs^[1][6].

AVMs in the skin may bleed, pulse as blood flows in and out, look like a bruised bump that is warm to the touch, or appear tender^[7][23].

AVMs in arms or legs may cause swelling, pain, weakness, or limit motion. The affected limb may grow longer and larger than the same limb on the other side^[7][23].

AVMs in the lungs may cause tiredness, shortness of breath, or coughing up blood^[6][7].

AVMs in the stomach or intestines may cause bleeding ranging from mild to severe. A child may vomit blood or have dark, tarry bowel movements^[7].

AVMs change and grow over time. As a child grows, an AVM can hurt, swell, or bleed. Starting at puberty or young adulthood, it may cause more problems^[7][21]. Bleeding from an AVM can be hard to stop, and frequent bleeding may lead to anemia (a low number of red blood cells)^[23].

How are they diagnosed?

To diagnose an AVM, doctors review symptoms and perform a physical examination^[2][5]. They may listen for a sound called a bruit, which is a whooshing sound caused by blood quickly flowing through the abnormal vessels. It sounds like water rushing through a narrow pipe^[9].

Doctors often find an AVM during an exam because they can feel a pulse in its vessels^[23]. Suspicion of a heart defect should be raised by feeding difficulties in association with rapid breathing, sweating, and difficulty breathing, or severe growth impairment in infants^[1].

Several imaging tests may be used to confirm the diagnosis and understand the extent of the malformation:

Magnetic resonance imaging (MRI) uses powerful magnets and radio waves to create detailed images of tissues. It can pick up on small changes in body structures^[9].

Magnetic resonance angiography (MRA) captures the pattern, speed, and distance of blood flow through irregular vessels^[7][9].

CT scan uses X-rays to create images and can help show bleeding^[9].

CT angiography combines a CT scan with injection of a special dye to help find an AVM that is bleeding^[9].

Cerebral angiography (also called arteriography) uses a special dye injected into an artery to highlight blood vessels on X-rays. This test can provide highly detailed images of the arteries and veins and additional information about an AVM^[5][9].

Doppler ultrasound uses high-frequency sound waves to check blood flow and can help diagnose an AVM^[7][21].

Genetic testing may be recommended if a doctor suspects an inherited disorder^[5].

Treatment options

Treatment of arteriovenous malformations depends on the type of AVM, its location, symptoms, and the individual’s general health^[1]. The choice of treatment is very individual and depends on the AVM’s complexity, how easy it is to reach surgically, and whether removing it would risk interfering with vital functions^[5].

In most cases, AVMs are removed by surgery if this option is safe and possible^[5]. Treatment strategies may include:

Surgical excision involves the complete removal of the AVM. Even after what appears to be complete removal, recurrence may still occur. A partial excision of an AVM does not appear to make recurrence worse, as was previously thought^[11]. Complications from surgical removal are more frequent but less devastating than complications from other treatments^[11].

Endovascular embolization is a minimally invasive technique that closes off as much blood flow as possible to the AVM. If the AVM is complex or supplied by deep, hard-to-reach blood vessels, embolization may be recommended before surgery to make the operation easier and safer^[5][13]. During this procedure, a doctor inserts a catheter or needle and uses X-ray guidance to inject materials that block the abnormal vessels^[13][15]. Embolization alone is effective in controlling symptoms but may be associated with an increased AVM size^[11].

Radiosurgery uses focused radiation beams to damage the AVM and cause it to close over time^[9].

Medications may be used to manage symptoms such as headaches or seizures^[1].

Observation may be appropriate for some AVMs that are not causing problems. Regular monitoring is important because AVMs can change over time^[1].

Sometimes treatment requires several stages to fully address the entire malformation^[13]. Once diagnosed, an AVM can often be treated to prevent or reduce the risk of complications^[2].

Living with the condition

Many children born with vascular malformations face ongoing challenges that need to be managed throughout their lives. Even if a child feels well, lifelong monitoring and care is usually needed^[17].

Follow-up care should follow the schedule of routine care for healthy babies with some modifications^[1]. It is important to find a heart team or medical team with expertise in managing congenital vascular malformations^[17]. Regular checkups with a primary care doctor and specialists are essential, even when symptoms are not present^[1].

Parents and families should understand the child’s specific condition and ask lots of questions. Learning about what the condition means for the child’s health now and in the future is important^[17]. Keeping organized records is helpful, including details about the type of malformation, every test and procedure performed, medications taken, and results from imaging tests^[17].

Helping children adopt heart-healthy habits early on is important. This includes eating well, getting appropriate exercise, not smoking, and managing stress^[17]. Most people with congenital vascular malformations can be physically active, though the amount and type of activity depends on the specific condition. Families should ask their doctor how much and what kinds of physical activity are safe^[1].

It is important to empower children to learn about their condition and become resilient. Parents should encourage open communication about how the child feels and help them form respectful relationships with their healthcare team^[17]. This heart condition does not define the child^[17].

Anxiety and feelings of uncertainty are very common among people with congenital vascular conditions and their families. Developing coping strategies early in life is important^[17]. One of the main roles for doctors and healthcare providers is to help parents put the diagnosis in perspective by clarifying expectations and answering specific questions^[1].

Overall patient and parent satisfaction with treatment tends to be high with respect to improvement in outcome^[11]. With increasing understanding of vascular malformations and evolution of treatment techniques, complications are expected to decrease and results are expected to improve^[11].