Health Library

What Is a Single Ventricle Defect?

The heart has four chambers, a left atrium and right atrium and a left ventricle and right ventricle. Having a single ventricle defect means that only one ventricle works well enough to pump blood.

What Are the Signs & Symptoms of a Single Ventricle Defect?

A newborn with a single ventricle defect can have:

• trouble breathing
• trouble feeding
• blue or grayish color of the skin and nails
• lethargy (very little activity)
• weak pulses in the arms and legs
• few wet diapers

These signs can start a few hours to a day or so after the birth. Without treatment, the baby’s blood pressure will fall too low to meet the body’s needs. Usually, though, doctors find the problem before the baby’s birth.

What Are the Types of Single Ventricle Defects?

Single ventricle defects include:

• Hypoplastic Left Heart Syndrome (HLHS)
• Tricuspid Atresia
• Double Outlet Right Ventricle (DORV)
• Pulmonary Atresia
• Atrioventricular Canal Defect
• Ebstein Anomaly

What Causes a Single Ventricle Defect?

Most cases of single ventricle defects happen in the developing heart during the first 8 weeks of pregnancy. Some might be due to a combination of genes and things in the baby’s and mother’s environment during this early stage.

How Is a Single Ventricle Defect Diagnosed?

Doctors find most single ventricle defects during pregnancy by doing a fetal echocardiogram (“echo”). If not, they diagnose them shortly after a baby’s birth with an echocardiogram. An echo is a completely safe and painless test that uses ultrasound (sound waves) to build a series of pictures of the heart.

Babies born with a single ventricle defect that wasn’t found before birth may become very ill. The exact symptoms will depend on the defect causing the single ventricle.

How Is a Single Ventricle Defect Treated?

Single ventricle defects are treated by two or three surgeries. The first surgery varies, depending on the diagnosis. But the second and third surgeries are usually the same no matter what kind of heart defect a child has.

The goal of the surgeries is to rebuild the heart and make sure that it:

• pumps blood out to the body
• returns the blood to the lungs (without being pumped by the heart as it would be in a child with two normal ventricles)
• returns the blood to the heart

Surgeries can include:

• Norwood Procedure
• Glenn Procedure
• Fontan Procedure

What Else Should I Know?

Other procedures may be needed, depending on a child’s diagnosis. But by the time children have the Fontan procedure, they will have similar medical care, challenges, and potential complications.

Other procedures kids might need include:

• cardiac catheterization
• electrophysiologic (EP) study: to check the heart’s electrical system and to look for abnormal heartbeats
• Holter monitor: an EKG done over a long period of time, usually 24 hours or more
• MRI and/or CT scan
• frequent echocardiograms
• stress tests 

All babies with a single ventricle will need care and surgery before they go home from the hospital after their birth. Then, they’ll be enrolled in a single ventricle program, and an expert care team will monitor them very closely.