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Hypoplastic Left Heart Syndrome Fact Sheet
What is hypoplastic left heart syndrome (HLHS)?
Hypoplastic left heart syndrome (HLHS) is a complex and rare heart condition. Children with HLHS have a combination of related heart problems
A healthy heart is a strong, muscular pump that pushes blood through the circulatory system to carry oxygen and nutrients to the body. The heart has four chambers -- two on the right and two on the left. Blood is pumped through these chambers and regulated by valves that open and close like tiny doors, so that blood can move in only one direction.
After its trip through the body to deliver oxygen, blood is a blue color because it’s no longer oxygen-rich. The blue blood returns to the heart through the right chambers and is pumped through the pulmonary artery into the lungs. In the lungs, it picks up more oxygen and becomes bright red. It then goes back through the pulmonary vein to the left chambers and is pumped through the aorta and out into the body again.
If your baby is born with HLHS, the chambers and arteries on the left side of the heart are small and underdeveloped with valves that don’t work properly. Since the left side can’t pump effectively, the right side of the heart must take on double the work and pump to both the lungs and the rest of the body.
A newborn baby with HLHS may appear to be well during the first hours or even days of life. However, a day or two after birth, the natural openings between the right and left sides of the heart close. That is normal, but in a baby with HLHS, it can be fatal because it leaves the overworked right side of the heart no way to pump blood to the body.
What causes HLHS?
Hypoplastic left heart syndrome occurs during the first eight weeks of fetal growth when the baby's heart is developing. The cause is unknown. However, if your family has one child with HLHS, the risk of having another with the same condition is higher than the recurrence rate for other congenital heart defects. This may mean genetics play a role. It's possible for a fetus to be diagnosed with HLHS through an ultrasound exam as early as the first trimester.
HLHS comprises 4-8% of all congenital heart defects. It occurs in up to four out of every 10,000 live births. HLHS appears slightly more often in boys than in girls. Beyond family history, there are no clear risk factors for it, and no known way to prevent it.
What are the signs and symptoms?
Usually, babies born with hypoplastic left heart syndrome are critically ill right away. Signs and symptoms vary, but may commonly include:
If the natural connections between the heart's left and right sides are allowed to close naturally a day or two after birth, the child may go into shock. Symptoms of shock include:
A baby in shock may be either conscious or unconscious. If you suspect your baby is in shock, dial 911 right away.
How is it diagnosed?
A clear diagnosis is the first step to treatment. A pediatric cardiologist (a children’s heart doctor) can use several tests to confirm your child’s diagnosis. These tests may include:
How is it treated?
Due to the advances in medical science in recent years, babies born with hypoplastic left heart syndrome today have a much improved outlook.
Once diagnosed, your child’s specific treatment may vary, depending on his or her individual needs. Your child will probably be admitted to the intensive care unit (ICU) or special care nursery and may be placed on oxygen or a ventilator to help with breathing. Intravenous (IV) medications may be given to assist heart and lung function and stop the two sides of the heart from closing naturally. Your baby’s doctor may also recommend an atrial septostomy, which is a procedure to create a helpful opening between the heart’s upper chambers.
For babies born with HLHS, there are two treatment options: a heart transplant, or far more commonly, a series of surgeries to reconstruct the heart to compensate for the otherwise-fatal defects. The procedures, which Children’s helped pioneer, are:
The second surgical option is a complete heart transplant. Babies with HLHS may need special medications while waiting for a donor heart to become available.
After surgery or a transplant, your baby will need lifelong follow-up care with a heart doctor who specializes in congenital heart disease. Some medication may be necessary to regulate heart function. If your baby receives a heart transplant, he or she will need to take anti-rejection medication for the rest of his or her life to combat rejection of the new heart.
Later in life, children who have had either treatment for hypoplastic left heart syndrome sometimes tire easily from exercise, experience heart rhythm abnormalities or blood clots, or have attention deficit hyperactivity disorder (ADHD).Your child's cardiologist may also recommend that your child limit physical activity and take antibiotics before dental procedures to prevent infections.
About treatment for hypoplastic left heart syndrome at Children's
Hypoplastic left heart syndrome is treated through Children’s cardiovascular program one of the largest and oldest pediatric cardiovascular programs in the region. Team members consistently achieve treatment results that are among the best in the nation. Each year, care is provided for thousands of the regionšs sickest children with heart conditions, including fetuses, newborns, infants, children, adolescents, and adult, long-term patients with pediatric cardiovascular conditions.
For more information, please call Children's Heart Clinic at 1-800-938-0301.
Heart with hypoplastic left heart syndrome
(From Pritchet & Hull Assoc., Inc.)