Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome is a congenital heart defect present at birth. It is a rare heart condition that affects the lower left chamber of the heart. the left ventricle is very small, the valves on the left side of the heart (aortic and mitral) do not work properly and the main artery leaving the heart (aorta) is smaller than normal.

This condition means that the left side of the heart will not be able to pump effectively to pump blood to the body, so the right side of the heart must do more work to compensate.

In a day or two after birth the natural openings between the right and left sides of the heart close. This closing which occurs naturally and normally does not affect the normal healthy newborn, can prove fatal to the baby with this congenital heart condition as now the right side of the heart no longer has a way to pump blood to the body.

Medication can be given to prevent the holes from closing between the left and the right sides. A heart transplant or heart surgery will be necessary to treat hypoplastic left heart syndrome if the baby is to survive. In the past, few babies survived; now the outlook is more promising for these babies.

HLHS Symptoms:

    Critically ill at birth

    Grayish-blue skin color

    Rapid and difficulty breathing

    Poor feeding

    Hands and feet are cold


If the natural holes on the left and right sides (foramen ovale and ductus arteriosus) are allowed to close the baby will go into shock and may die.

Symptoms of shock:

    Clammy and cool skin that may also be pale or gray in color

    Rapid and weak pulse

    Slow, shallow or very rapid breathing

    Dilated pupils (eyes)

    Eyes that seem to stare (lackluster)

    May be conscious or unconscious

    A baby in shock needs medical treatment right away as this is an emergency.


The causes are unknown. All that is known is that it occurs during fetal development.

Genetics does play a role in hypoplastic left heart syndrome.

Seeking Medical Attention:

If your baby has any of these symptoms seek medical attention immediately:

    Skin color – gray or blue

    Breathing that is rapid or seems difficult in any way.

    Does not feed well

    Hands and feet are cold

    Baby is always sleepy

    Shock symptoms are an emergency and must be given immediate medical care:

    cold, clammy skin that is blue or gray in color

    rapid and weak pulse

    breathing that is not normal (slow, shallow, or very rapid)

    Pupils of the eyes are dilated

    Eyes appear to be lackluster and as if they are staring

Prenatal Screening:

Today there is advanced ultrasound technology that can detect heart defects like hypoplastic left heart syndrome. This condition can often by detected by ultrasound as early as the first trimester.

Diagnosis after birth:

A physician or other healthcare professional may suspect hypoplastic left heart syndrome, if the baby is gray or bluish in skin color or has difficulty breathing or if the medical professional hears a heart murmur.

An echocardiogram will be performed to help make the diagnosis. This test will reveal the smaller than normal left ventricle and aorta and also track the blood flow from right ventricle into the aorta. Other heart defects can also be detected by the echocardiogram.