Single ventricle defects

What are single ventricle defects?

Single ventricle defects are a type of rare congenital (present at birth) disorders where the lower chambers of your child’s heart may be smaller, underdeveloped or missing a valve. There are many different types of single ventricle defects in children and they can lead to other health complications, such as learning disabilities and liver problems.

Recent research has made great strides in improving the quality of life of children with these congenital heart defects (heart problems a child is born with). Now, kids with these conditions are living longer, healthier lives than ever.

Children with single ventricle defects are born with hearts that only have one ventricle large or strong enough to pump blood effectively (instead of two). Ventricles are the lower chambers of the heart that help pump blood with oxygen in it to the body. Single ventricle heart defects are also called single ventricle lesions or anomalies.

Single ventricle defects can cause other health problems for children, including liver problems, lower exercise stamina, irregular heartbeats, and problems with their lymphatic system, which helps keep their immune and circulatory systems healthy.

What are the different types of single ventricle defects?

There are several types of single ventricle defects.

• Tricuspid atresia - This is when the tricuspid valve, which divides the right upper chamber (atrium) and the right lower chamber (ventricle) of your child’s heart, is poorly developed, missing, or has a hole in it. This causes your child’s blood to flow in the wrong direction inside of their heart.
• Hypoplastic left heart syndrome (HLHS)  - This is when the left side of the heart does not develop correctly. This leads to the child’s body not circulating oxygen correctly.
• Mitral valve atresia - This is when the mitral valve of the heart does not develop correctly. This valve is supposed to open to let blood into the left ventricle (lower chamber) from the left atrium (upper chamber) during a heartbeat and then closes when the left ventricle is full. This can lead to your child’s blood to flow in the wrong direction or leak back to the left atrium.
• Mitral valve stenosis - This is when the mitral valve’s two leaflets that typically open and close to help facilitate blood flow are fused, too thick or have another structural defect. This can lead to parts of your child’s heart becoming starved for blood and oxygen and affect their other organs.
• Double inlet left ventricle  - A heart with a large left ventricle, which is responsible for sending oxygen-rich blood to the rest of the body, and a small right ventricle, which is responsible for sending blood back to the lungs when it needs more oxygen.
• Pulmonary atresia with intact ventricular septum - This is when the pulmonary valve, tricuspid valve, and right ventricle all do not develop fully, which can lead to your child not having enough oxygen in their blood to support their body’s needs.
• Ebstein’s anomaly - This is when the tricuspid valve is in the wrong position and the valve's flaps are malformed, so it does not open and close properly. This can lead to blood leaking back through the valve, making your child’s heart work less efficiently. Learn more about the Cone procedure.
• Atrioventricular canal defect - A combination of heart problems including a hole between the heart's chambers and problems with the valves that control blood flow in the heart. This allows extra blood to flow to the lungs, causing the heart muscle to work too hard and enlarge.

How are single ventricle defects diagnosed?

Every child in Texas receives a congenital heart screening at birth. As part of this screening, their oxygen levels are measured to identify any single ventricle defects.

More and more single ventricle defects are discovered in utero, meaning during pregnancy. They can also be identified in the first few days or weeks of life through the state-mandated screening that every child in Texas receives at birth.

At Children’s Health, we perform various types of imaging to get clear pictures of what is going on in your child’s heart.

• Echocardiogram - The first-line tool to diagnose a defect, this test uses ultrasound (high-frequency sound waves) from a hand-held wand to provide pictures of your child’s heart's valves and chambers to help clarify how well it is pumping blood
• Magnetic resonance imaging (MRI) - This is a tube-like machine that uses a strong magnetic field and radio waves to create detailed images of the heart’s structure and function.
• Computerized tomography (CT) scans - This is a donut-shaped machine that combines 2-dimensional X-ray images from different angles and uses computer processing to create a 3-dimensional image, made up of cross-sectional images (slices), of the heart.
• Cardiac catheterization - Cardiologists insert a long thin tube called a catheter into an artery or vein in your child’s groin, neck or arm and thread it through their blood vessels to their heart. Once there, the catheter can measure oxygen levels and check the pumping function of your child’s heart.
• Dual MRI and catheterization - Children’s Health specialists combine an MRI with a catheterization into one procedure in order to help kids avoid going under anesthesia more often than absolutely necessary.

How are single ventricle defects treated?

• Palliation - Most kids with single ventricle heart defects need medical care soon after birth. Pediatric cardiologists treat single ventricle defects with a series of open-heart procedures called palliation. During this process, surgeons reconfigure the heart and circulatory system over the course of several years. These palliations are often a series of 2-3 procedures that aim to reroute your child’s blood to more effectively circulate oxygen and nutrients to their body.
• Cardiac catheterization - Many kids may also need a cardiac catheterization during childhood. These procedures maximize the parts of your child’s heart that work effectively to give them better outcomes than they would have without surgery.
• Lymphatic system - Single ventricle defects can also cause your child’s lymphatic system to drain incorrectly. Children’s Health is now one of the few providers in the country with the ability to treat this issue.

Why Children's Health?

We know that no two children and no single ventricle defects are alike and we’ll work with you to cater our care teams to your child and family’s specific needs. Treating these complex heart defects is a journey that takes a team of specialized doctors, all of whom are advocates for your child.

Our experts will help support you and your child by:

• Monitoring your child’s health between procedures through our Safe at Home program. This includes monitoring their sleep and eating schedules and other key indicators of health.
• Anticipating, identifying, and managing any learning disabilities associated with single ventricle defects and helping your child feel supported and confident at school.
• Using child-specific diagrams to help your child understand their condition.
• Helping lessen the need for anesthesiology by helping children relax with toys, games, emotional support animals and more.
• Offering family resources for transportation and accommodations.