Diagnosis

Before birth

It's possible for a baby to be diagnosed with hypoplastic left heart syndrome while still in the womb. Your doctor might be able to identify the condition on a routine ultrasound exam during the second trimester of pregnancy.

After birth

After your baby is born, a doctor might suspect a heart defect, such as hypoplastic left heart syndrome, if your baby has grayish-blue skin color or has trouble breathing. Your baby's doctor might also suspect a heart defect if he or she hears a heart murmur — an abnormal sound caused by turbulent blood flow — when listening to the heart with a stethoscope.

Doctors usually use an echocardiogram to diagnose hypoplastic left heart syndrome. This test uses sound waves that bounce off your baby's heart to produce moving images that can be viewed on a video screen.

If your baby has hypoplastic left heart syndrome, the echocardiogram will show a smaller than normal left ventricle and aorta. The echocardiogram might also show abnormal heart valves.

Because this test can track blood flow, it also shows blood moving from the right ventricle into the aorta. In addition, an echocardiogram can identify associated heart defects, such as an atrial septal defect.