Cor triatriatum is a rare congenital heart defect, meaning your child was born with it. The name “cor triatriatum” comes from Latin. It means “heart with three atria.” Normally, the heart has two atria (upper chambers). With cor triatriatum, one atrium is split into two spaces by a sheet of tissue, resulting in “three” atria. The sheet of tissue, or membrane, in the atrium can block or slow the flow of blood through the heart.
There are two main types of cor triatriatum:
Cor triatriatum can cause pressure to build up in the lungs and heart. If the membrane creates a significant blockage, the child can have trouble breathing and other serious problems. With treatment, most children will lead active, healthy lives.
The heart has four chambers that pump blood through the body. Two are on the top and two are on the bottom. They are:
Blood normally flows through the heart in this order:
For the heart to work well, blood must move easily through the atria. With cor triatriatum, the membrane inside an atrium can slow or block this normal blood flow.
In cor triatriatum, a thin membrane forms inside one of the atria during heart development. This membrane divides the atrium into two smaller chambers.
The membrane usually has one or more small openings. Blood must pass through these openings to move through the heart. If the openings are large, blood may flow normally and symptoms may be mild. If the openings are small, blood flow can become blocked. This can cause pressure to build in the lungs and heart.
More severe blockages may lead to breathing problems or other symptoms. The size of the membrane opening often determines how severe the condition is.
Cor triatriatum is a congenital heart defect. This means it develops while the heart is forming during early pregnancy, and the baby is born with it.
Normally, the atria form as single open chambers. But with cor triatriatum, a membrane remains inside the atrium instead of disappearing during development. Doctors do not always know why this happens.
Some children with cor triatriatum also have other congenital heart defects, including:
These differences can affect how blood flows through the heart.
Cor triatriatum symptoms in children can vary depending on how much the membrane blocks blood flow. Some children have symptoms soon after birth. Others may not show symptoms until later in childhood.
Babies with more severe blockage may have:
Children with milder blockage may develop symptoms later, such as:
Some children with larger membrane openings may have few or no symptoms for many years.
A cor triatriatum diagnosis begins with a physical exam. Doctors listen for a heart murmur, which is an unusual sound caused by abnormal blood flow. They may also check breathing patterns and oxygen levels.
If doctors suspect a heart problem, they may order imaging tests to look at the heart and how blood flows through it.
The most common tests used to diagnose cor triatriatum include:
In some cases, doctors can detect cor triatriatum before birth using fetal echocardiography during pregnancy. A fetal echocardiogram may be ordered if there is concern for a cardiac abnormality on a baby’s regular anatomy ultrasound, or if there is a family history of congenital heart disease.
Treatment depends on how much the membrane blocks blood flow and whether the child is showing symptoms.
Some children with mild obstruction may not need immediate treatment. Doctors may recommend:
Children with significant blockage usually need surgery. During surgery, the heart surgeon removes the membrane that divides the atrium. Surgery is done by opening the chest to access the heart. The child will be on a heart-lung machine, which takes over the work of their heart and lungs during the surgery.
If other heart defects are present, they may be repaired during the same surgery.
Removing the membrane allows blood to flow normally through the heart again. For many children, surgery corrects the problem completely.
Children will recover initially in the intensive care unit (ICU) and may stay in the hospital for two days to three weeks after surgery for cor triatriatum. Full recovery takes a few weeks. During recovery, doctors watch for normal heart rhythm and good blood flow.
Follow-up visits help doctors monitor heart function and check healing after surgery.
Most children continue to see a cardiologist as they grow.
The outlook for children with cor triatriatum is usually very good, especially after successful surgery.
Most children recover well and can live active lives. Many children can take part in normal activities, including sports, once their heart has healed.
Regular heart checkups help ensure the heart continues to work normally. Some patients continue care with specialists who focus on adult congenital heart disease later in life.
Families can help children stay healthy by supporting normal growth and activity. Most children benefit from:
Children with congenital heart conditions may also need emotional support as they grow. Support can address any stress, anxiety or uncertainty about their health. Care teams can help families find resources and support groups.
Cor triatriatum is a very rare congenital heart defect. It accounts for a small percentage (0.1%-0.4%) of heart defects seen in children.
In some cases, doctors can detect it during pregnancy using a fetal echocardiogram.
Some children need surgery to remove the membrane. Others with mild cases may only need monitoring.
Most children who receive treatment recover well and live active, healthy lives.
The schedule depends on your child’s condition and treatment. Many children need periodic cardiology visits as they grow.
Last Updated 08/2026
Learn more about our editorial policy.
3333 Burnet Avenue, Cincinnati, Ohio 45229-3026
© 2026 Cincinnati Children's Hospital Medical Center. All rights reserved.
