Hypoplastic left heart syndrome

Overview

Hypoplastic left heart syndrome is a complex and rare heart defect present at birth (congenital). The left side of the heart is critically underdeveloped in hypoplastic left heart syndrome.

If your baby is born with hypoplastic left heart syndrome, the left side of the heart can't effectively pump blood to the body. Instead, the right side of the heart must pump blood to the lungs and to the rest of the body.

Medication to prevent closure of the connection (ductus arteriosus) between the right and left sides, followed by either surgery or a heart transplant, is necessary to treat hypoplastic left heart syndrome. With advances in care, the outlook for babies born with hypoplastic left heart syndrome is better now than in the past.

Symptoms

Babies born with hypoplastic left heart syndrome usually are seriously ill soon after birth. Hypoplastic left heart syndrome symptoms include:

  • Grayish-blue skin color (cyanosis)
  • Rapid, difficult breathing
  • Poor feeding
  • Cold hands and feet
  • Weak pulse
  • Being unusually drowsy or inactive

If the natural connections between the heart's left and right sides (foramen ovale and ductus arteriosus) are allowed to close in the first few days of life in a baby with hypoplastic left heart syndrome, he or she can go into shock and may die. Signs of shock include:

  • Cool, clammy skin that may be pale or gray
  • A weak and rapid pulse
  • Abnormal breathing that may be either slow and shallow or very rapid
  • Lackluster eyes that seem to stare

A baby who is in shock may be conscious or unconscious. If you suspect your baby is in shock, immediately call 911 or your local emergency number.

When to see a doctor

It's likely that your baby would be diagnosed with hypoplastic left heart syndrome either before birth or soon after. However, you should seek medical help if you notice that your baby has the following symptoms:

  • Grayish-blue skin color
  • Rapid, difficult breathing
  • Poor feeding
  • Cold hands and feet
  • Weak pulse
  • Being unusually drowsy or inactive

If your baby has any of the following signs of shock, call 911 or your local emergency number right away:

  • Cool, clammy skin that may be pale or gray
  • A weak and rapid pulse
  • Abnormal breathing that may be either slow and shallow or very rapid
  • Lackluster eyes that seem to stare

Causes

Hypoplastic left heart syndrome occurs during fetal growth when the baby's heart is developing. The cause is unknown. However, if your family has one child with hypoplastic left heart syndrome, the risk of having another with a similar condition is increased.

A normal heart has four chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout the body — the heart uses its left and right sides for different tasks.

The right side moves blood to the lungs. In the lungs, oxygen enriches the blood, which then circulates to the heart's left side. The left side of the heart pumps blood into a large vessel called the aorta, which circulates the oxygen-rich blood to the rest of the body.

What happens in hypoplastic left heart syndrome

In hypoplastic left heart syndrome, the left side of the heart can't properly supply blood to the body because the lower left chamber (left ventricle) is too small or in some cases may not even exist. In addition, the valves on the left side of the heart (aortic valve and mitral valve) don't work properly, and the main artery leaving the heart (aorta) is smaller than normal.

For the first several days of life, the right side of the heart can pump blood both to the lungs and to the rest of the body through a blood vessel that connects the pulmonary artery directly to the aorta (ductus arteriosus). The oxygen-rich blood returns to the right side of the heart through a natural opening (foramen ovale) between the right chambers of the heart (atria). When the foramen ovale and the ductus arteriosus are open, they are referred to as being "patent."

If the ductus arteriosus and the foramen ovale close — which they normally do after the first day or two of life — the right side of the heart has no way to pump blood out to the body. Keeping these connections open with medication is necessary for survival in the first few days of life in babies with hypoplastic left heart syndrome. This will keep blood flowing to the body until heart surgery is performed.

Chambers of the heart

A normal heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of your heart. The heart valves, which keep blood flowing in the right direction, are gates at the chamber openings.

Hypoplastic left heart syndrome

In this condition, the left side of the heart — including the aorta, aortic valve, left ventricle and mitral valve — is underdeveloped (hypoplastic). As a result, the body doesn't receive enough oxygenated blood.

Risk factors

If you already have a child with hypoplastic left heart syndrome, you have a higher risk of having another baby with this condition or a similar condition.

Beyond family history, there are no clear risk factors for hypoplastic left heart syndrome.

Complications

Without surgery, hypoplastic left heart syndrome is fatal, usually within the first few weeks of life.

With treatment, many babies survive, although most will have complications later in life. Some of the complications may include:

  • Tiring easily when participating in sports or other exercise
  • Heart rhythm abnormalities (arrhythmias)
  • Fluid buildup in the lungs, abdomen, legs and feet (edema)
  • Growth restriction
  • Formation of blood clots that may lead to a pulmonary embolism or stroke
  • Developmental problems related to the brain and nervous system
  • Need for additional heart surgery or transplantation

Prevention

There's no known cause of hypoplastic left heart syndrome, so there's no known way to prevent the condition. If you have a family history of heart defects, or if you already have a child with a congenital heart defect, before getting pregnant consider talking with a genetic counselor and a cardiologist experienced in congenital heart defects.

Diagnosis

Before birth

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

After birth

After your baby is born, his or her doctor may 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 may also suspect a heart defect if he or she hears a heart murmur when listening to the heart with a stethoscope — an abnormal whooshing sound caused by turbulent blood flow.

Doctors usually use an echocardiogram to diagnose hypoplastic left heart syndrome. This test uses high-pitched 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 may 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.

Treatment

Hypoplastic left heart syndrome is treated through several surgical procedures or a heart transplant. Your doctor will discuss with you the treatment options for your child.

If the diagnosis has been made before the baby is born, doctors usually recommend delivery at a hospital with a cardiac surgery center.

Before surgery

Your baby's doctor may recommend several options to help manage your baby's condition before surgery or transplant. They may include:

  • Medication. The medication alprostadil (Prostin VR Pediatric) helps dilate the blood vessels and keeps the ductus arteriosus open.
  • Breathing assistance. If your baby has trouble breathing, he or she may need help from a breathing machine (ventilator), which ensures adequate oxygen delivery.
  • Intravenous fluids. Your baby will receive fluids through a tube inserted into a vein.
  • Feeding tube. If your baby has trouble or gets tired while feeding, he or she may be fed through a feeding tube.
  • Atrial septostomy. This procedure creates or enlarges the opening between the heart's upper chambers (atria) to allow more blood flow between the right atrium to the left atrium if the foramen ovale closes or is too small. If your baby already has an atrial septal defect, an atrial septostomy may not be necessary.

Surgery

Your child will likely need several surgical procedures to treat hypoplastic left heart syndrome. Surgeons perform these procedures in three stages. These procedures are designed to create normal blood flow in and out of the heart so the body gets the oxygen-rich blood it needs.

  • Norwood procedure. This surgery is usually performed within the first two weeks of your child's life. Several forms of this procedure may be performed.

    Surgeons reconstruct the aorta and connect it directly to the heart's lower right chamber (right ventricle). Surgeons insert a tube (shunt) that connects the aorta to the arteries leading to the lungs (pulmonary arteries), or they place a shunt that connects the right ventricle to the pulmonary arteries. This procedure allows the right ventricle to effectively pump blood to both the lungs and the body.

    In some cases, doctors may perform a hybrid procedure. Surgeons implant a stent in the ductus arteriosus to maintain the opening between the pulmonary artery and aorta, place bands around the pulmonary arteries to reduce blood flow to the lungs, and create an opening between the atria of the heart.

    After this procedure, your baby's skin will still have a blue cast because oxygen-rich blood and oxygen-poor blood continue to mix within the heart. Once your baby successfully passes through this stage of treatment, the odds of survival may increase, but he or she may still be at risk of death due to complications.

  • Bi-directional Glenn procedure. This procedure is generally the second operation and is performed when your child is between 3 and 6 months of age. In this procedure, doctors remove the first shunt attached to the pulmonary arteries, and then connect one of the large veins that normally returns blood to the heart (the superior vena cava) to the pulmonary artery instead. If surgeons previously performed a hybrid procedure, they'll conduct additional steps during this procedure.

    This procedure reduces the work of the right ventricle by allowing it to pump blood mainly to the aorta. It also allows most of the oxygen-poor blood returning from the body to flow directly into the lungs without a pump.

    After this procedure, all the blood returning from the upper body is sent to the lungs, so blood with more oxygen is pumped to the aorta to supply organs and tissues throughout the body.

  • Fontan procedure. This procedure is usually performed when your child is between 18 months and 4 years of age. During this procedure, the surgeon creates a path for the oxygen-poor blood in one of the blood vessels that returns blood to the heart (the inferior vena cava) to flow directly into the pulmonary arteries. The pulmonary arteries then transport the blood into the lungs.

    This procedure allows the rest of the oxygen-poor blood returning from the body to flow to the lungs. After this procedure, there's no mixing of oxygen-rich and oxygen-poor blood in the heart, and your child's skin will no longer look blue.

Another surgical option is a heart transplant, especially when the associated heart defects are complex. Babies with hypoplastic left heart syndrome can be considered for a transplant. After a heart transplant, your child will need lifelong medications to prevent the body from rejecting the donor heart.

Follow-up care

After surgery or a transplant, your baby will need lifelong follow-up care with a cardiologist trained in congenital heart diseases to monitor his or her heart health. Some medications may be necessary to regulate heart function. Various complications may occur over time and may require further treatment or medications.

Your child's cardiologist will tell you whether your child needs to take preventive antibiotics before certain dental or other procedures to prevent infections. In some cases, he or she may also recommend that your child limit physical activity.

Follow-up care for adults

As an adult, you'll transition from a pediatric cardiologist to a cardiologist trained in congenital heart disease in adults. It's only recently that advances in surgical care have resulted in children with hypoplastic left heart syndrome surviving into adulthood, so it's not yet clear the exact challenges an adult with the condition may face. That's why you'll need regular, lifelong follow-up care to monitor for any changes in your condition.

If you're a woman and you're considering pregnancy, discuss pregnancy risks and birth control options with your doctor. Pregnancy typically isn't recommended for someone with hypoplastic left heart syndrome.

However, some women with the condition have had healthy pregnancies and deliveries. But, during pregnancy, such a woman's risk of cardiovascular problems is higher than it is for a woman without hypoplastic left heart syndrome. The risk of having a baby with congenital heart disease is also increased if the mother has congenital heart disease.

Coping and support

It can be challenging to live with hypoplastic left heart syndrome or to care for a baby with the condition. Here are some strategies that may help make it easier:

  • Seek support. If you have a child with hypoplastic left heart syndrome, ask for help from family members and friends. It's important for caregivers to take breaks sometimes. Talk with your child's cardiologist about support groups and other types of assistance that are available near you.

    If you're a teen or an adult with hypoplastic left heart syndrome, ask your doctor if there are any support groups for adults with congenital heart conditions. It can be helpful to talk to other people who understand your challenges and triumphs.

  • Record your baby's health history. It's important to write down your or your baby's diagnosis, medications, surgery and other procedures and the dates they were performed, as well as the name and phone number of your or your child's cardiologist, emergency contact numbers for your or your child's doctors and hospital, and any other important information about your or your baby's care. It's also important to include a copy of the operative report from your or your child's surgeon in your records.

    This information will help you recall the care you or your child has received, and it will be useful for doctors who are unfamiliar with you or your baby to review your or your child's complex health history. This information is also helpful as your child grows into adulthood and transitions from pediatric to adult cardiology care.

  • Talk about your concerns. As your child grows, you may worry about activities in which he or she can safely participate. Talk with the cardiologist about which activities are best for your child. If some are off-limits, encourage your child in other pursuits rather than focusing on what he or she can't do. If other issues about your child's health concern you, discuss them with your child's cardiologist, too. As an adult, ask your doctor about what activities you can do, and if you have any questions or concerns.

Last Updated Aug 4, 2018


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