Scimitar Syndrome

Scimitar syndrome is a congenital heart defect with one or more pulmonary veins from your right lung draining into the inferior vena cava, or the right side of your heart, instead of the left. The unusual blood flow pattern (cardiac shunt) puts extra blood in your heart’s right side. Sometimes, your right lung may also receive blood from your aorta instead of your pulmonary arteries.

People with this syndrome often have a right pulmonary vein shaped like a scimitar, a curved Middle Eastern sword. You can see this shape on imaging.

In addition to the vein drainage issue, your right lung doesn’t fully develop. Neither does your right pulmonary artery, which carries blood to your lungs. Also, your heart may be on the right side of your chest instead of the left.

Symptoms can be severe in infants, while others don’t have symptoms as adults. People with symptoms or a large shunt need surgery to fix the drainage problem.

Scimitar syndrome is rare. Only about 1 to 3 out of every 100,000 babies are born with the condition. It’s twice as common in females as in males.

Other names for this syndrome include congenital venolobar syndrome and mirror-image lung syndrome.

This condition is a type of partial anomalous pulmonary venous return (PAPVR). It may lead to complications like pulmonary hypertension and Eisenmenger syndrome. Also, many people with scimitar syndrome have other heart or blood vessel problems. Some are born with several heart conditions.

Symptoms of scimitar syndrome

Sometimes, babies show scimitar syndrome symptoms right after birth. These symptoms include:

• Difficulty breathing while feeding
• Pale or grayish skin
• Rapid breathing
• Swelling (edema) in their legs, belly or around their eyes

Other times, children may grow into adults without showing any symptoms. Most adults with scimitar syndrome show no symptoms. Adults who do have symptoms often have repeat lung infections and shortness of breath (dyspnea) during physical activity.

Scimitar syndrome causes

Experts don’t know exactly what causes scimitar syndrome. It may be a problem with how your baby’s lung and blood vessels formed in the uterus.

How doctors diagnose this condition

Healthcare providers may use several tests to diagnose scimitar syndrome. These imaging tests tell providers about the size of your baby’s right lung and right pulmonary artery. They also show the heart on the wrong side of the chest and the pulmonary vein in the wrong place. Tests include:

• Chest X-rays that use radiation to take images of your child’s heart, lungs, airways and blood vessels
• CT scans that take X-rays from multiple angles to create detailed images of the inside of your baby’s body
• MRA that uses radio waves, magnets and a computer to assess blood vessels
• Echocardiograms that use ultrasounds before or after birth to evaluate your child’s heart and chest wall

Your provider may also do a cardiac catheterization (angiogram). They do this to look at your baby’s blood vessels and measure pressures in their lungs and body.

How is it treated?

Healthcare providers treat scimitar syndrome with surgery. If a provider finds the condition in a baby, they often operate within the first two months of life.

Your baby may need treatment for other conditions before surgery. If they have pulmonary hypertension, they’ll need care for that first. Some babies may need a provider to destroy abnormal arteries using a catheter. If a baby needs time to grow before surgery, they may receive medicine for heart failure symptoms first.

Adults who have scimitar syndrome only need a repair if they have severe symptoms, like repeat lung infections or a major shunt.

During surgery, a cardiac surgeon (heart doctor who does surgery) may:

• Reroute the pulmonary vein to the left side of your heart using patches
• Reroute the pulmonary vein to the left side by implanting it directly into the left side of your heart
• Remove the lung that’s too small (pneumectomy)

When should I see my healthcare provider?

If your baby gets a scimitar syndrome diagnosis, a healthcare provider will need to monitor them closely. After surgery, they’ll need follow-up visits. Their healthcare team will want to make sure that everything keeps working as it should after a repair.

If you’re an adult when you get this diagnosis, you may only need follow-up visits if you have surgery.

You may want to ask your healthcare provider:

• Do I need surgery for scimitar syndrome?
• What happens if I don’t have surgery?
• How can I manage my heart health with scimitar syndrome?

What can I expect if I have this condition?

Scimitar syndrome can be fatal for up to 4 out of 10 infants who have this syndrome and many other medical problems. An early diagnosis improves their outcome. Survival rates are better in people who don’t get symptoms until later in childhood or as adults.

People who have surgery for scimitar syndrome typically have excellent long-term outcomes. Most people have no further symptoms of this syndrome after surgery. In some people, especially babies and young children, the rerouted pulmonary vein may become narrow. They may need more treatment for this.

Some adults with scimitar syndrome don’t have symptoms. They may live healthy lives without needing surgery. But many adults with this syndrome have other heart conditions that need care. These conditions may affect their quality of life.

At some point, adults may need surgery if they start showing symptoms of scimitar syndrome, like severe shortness of breath or lung infections. Adults may also need special studies to find out whether they have high lung artery pressures.

What other conditions are associated with this syndrome?

Other heart conditions people with scimitar syndrome may have include:

• Atrial septal defect (ASD): Holes between the two upper chambers of your heart
• Horseshoe lung: When two parts of your lungs connect in an atypical way
• Patent ductus arteriosus: A fetal blood vessel doesn’t close like it’s supposed to after birth
• Pulmonary sequestration (accessory lung): A piece of disconnected lung tissue that doesn’t function or has an abnormal blood supply
• Ventricular septal defect (VSD): A hole between the two pumping chambers of your heart