Introduction

A heart defect is when the heart or the heart’s blood vessels do not grow (develop) the right way before birth. The words ‘congenital heart defect’ and ‘congenital heart disease’ both mean that the defect happened before the baby was born. A ‘single ventricle heart defect’ is one kind of congenital heart defect. This happens when one of the pumping chambers of the heart does not develop all the way. The Centers for Disease Control and Prevention (CDC) estimates that almost 1,000 babies are born with single ventricle heart defects each year in the United States.

Parents often think they did something to make this to happen to their baby. That is a normal response. In most cases, parents have no control over their baby’s condition and have not done anything to cause the problem. No one knows what causes single ventricle heart defects, but it may be because of the baby’s genes. If you have specific questions or concerns about you or your baby, talk with your doctor or nurse practitioner.

Diagnosing the Heart Defect

During pregnancy, there are many prenatal tests that can tell the doctor if your baby has a heart problem. However, some heart (cardiac) problems cannot be seen until after birth. The following are some prenatal tests that may be done:

• Prenatal ultrasound: Complex heart defects are usually found during a pregnancy (prenatal) ultrasound, which would show an abnormally-shaped heart. Your doctor will schedule a fetal echocardiogram to get more information.
• Fetal echocardiogram: A fetal echocardiogram is a special ultrasound used by a pediatric heart doctor (cardiologist) to look closely at your baby’s heart and surrounding blood vessels. The cardiologist will need to assess your baby after birth with an echocardiogram to confirm the diagnosis.

Postnatal Diagnosis (after baby is born):

• Echocardiogram: An echocardiogram is a special ultrasound used by a pediatric heart doctor (cardiologist) to look closely at your baby’s heart and surrounding blood vessels.
• Heart Catherization: A test to measure pressures in the heart, take pictures (angiography), and/or open any narrowings with a stent or balloon.
• Cardiac MRI: A test that uses radio waves, magnets, and a computer to create detailed pictures of the heart. Cardiac MRI can provide detailed information on the type and severity of heart disease.

Other Tests

Some congenital heart conditions are because of changes in DNA, or a baby’s genetic make-up. The doctors may suggest some of these genetic tests to find out more about your baby’s DNA:

• Cell-Free Fetal DNA testing: Your doctor can take a sample of your blood to look for copies of fetal (baby) DNA. This is only a screening test. A positive result means that there could be problems with the DNA. This should be confirmed with another test to be sure of the result. Other testing can be done before or after birth depending on the needs of the baby.
• Amniocentesis: A small sample of the amniotic fluid that surrounds the baby in the womb is taken and tested for DNA problems. This test is usually done in the middle of the second trimester. An amniocentesis can be used to confirm findings on the cell-free fetal DNA test.
• Testing the baby: After birth, a test is done with a sample of your baby’s blood to look for chromosome problems. This is called either a “karyotype” (basic chromosome study), or microarray (a more detailed look at genes).