Hypoplastic left heart syndrome (HLHS) is a heart defect where the left side of the heart doesn’t develop properly. This means it’s smaller and weaker, so the right side of the heart must work extra hard to pump blood to the rest of the body. 

At Nemours, we are experts at detecting heart problems early, including babies still in the womb — giving children the best chance. If your child is diagnosed with hypoplastic left heart syndrome, you can trust the pediatric heart specialists in our Nemours Cardiac Center.

Our board-certified, fellowship-trained pediatric cardiologists and cardiothoracic surgeons (specialists in surgical procedures of the chest, including the heart and lungs) are here to answer your questions, address your concerns, and offer treatment options, including hypoplastic left heart syndrome surgery. Our cardiac teams offer the latest in research-backed care, delivered with compassion.

In addition, we offer the Nemours app , which includes special features specifically for patients with HLHS and allows your child's cardiac care team to proactively monitor your child and potentially identify any emerging problems as quickly as possible. 

En español: Síndrome de corazón izquierdo hipoplásico  

Hypoplastic left heart syndrome (HLHS) is a rare birth defect of a baby's heart. The left side of the heart doesn't grow as it should, making it smaller and weaker than normal.

The left side of the heart is supposed to pump blood out to the body. But a baby's heart with HLHS can't do the job. This makes a baby very sick. Without medicines and a series of three surgeries to rebuild the heart, babies with HLHS won't survive.

The left side of the heart can't be fixed, so the goal of the surgeries is to rebuild parts of the heart and "redirect" the way blood flows to and from the body.

Soon after birth, a baby with HLHS needs around-the-clock care in a hospital for the first weeks or months of life.

How Does the Heart Work?

The heart is a muscle that pumps blood. It acts like two pumps in one. The pumps are called ventricles and each has an important job:

• The right ventricle gets blood from the body and pumps it out the pulmonary artery to the lungs. In the lungs, blood fills up with oxygen and gets rid of carbon dioxide.
• The left ventricle  gets the blood from the lungs and pumps it out through the aorta  to the body.

Because it pumps blood to the entire body, the left ventricle is a stronger pump than the right ventricle.

With hypoplastic left heart syndrome:

• The left ventricle and aorta are too small to pump enough blood to the body.
• The right ventricle, which is only supposed to pump blood to the lungs, pumps blood to the lungs and the body through an extra pathway called a patent ductus arteriosis (PDA) . That means the right ventricle gets overworked.
• Babies with HLHS are almost always born with an atrial septal defect (ASD) . This is a hole in the upper part of the heart. It lets blood with oxygen mix with blood low on oxygen. Then the right ventricle pumps the blood to the lungs and the body.
   

What Are the Signs and Symptoms of Hypoplastic Left Heart Syndrome?

Within a few hours to a day or so after birth, a newborn with undiagnosed HLHS may have:

• trouble breathing
• blue or grayish coloring of the skin and nails
• difficulty feeding
• lethargy (very little activity)
• weak pulses in the arms and legs
• few wet diapers

What Causes Hypoplastic Left Heart Syndrome?

HLHS is a birth defect that happens when a baby is growing in the womb. No one knows exactly what causes it, but it could have a mix of causes, including a baby's genes (DNA) .

Hypoplastic left heart syndrome can be diagnosed with:

• a prenatal ultrasound  scan
• chest X-ray
  
• electrocardiogram
• echocardiogram
  
• pulse oximetry  

How Is Hypoplastic Left Heart Syndrome Treated?

HLHS is first treated with medicines, and then a series of three surgeries. Without surgery, a baby won't survive. Treatment for HLHS starts as soon as the baby is born.

Medicines

Immediate treatment includes a medicine called prostaglandin. Prostaglandin keeps the PDA open so oxygen can get to the body.

Some babies need other medicines to help balance how much blood goes to the lungs and how much goes to the body.

Also if the ASD is too small, it might be made bigger. This is done with a cardiac catheterization   procedure or by surgery.

The Surgeries

Because the left ventricle and aorta are too small, the goals of the surgeries are to:

• Use the right ventricle to pump oxygen to the body.
• Send the blood coming back from the body straight to the lungs without having to pass through the heart.

Surgeries are done in stages as a baby grows. They are (in order):

1. Norwood Procedure
   
2. Glenn Procedure
   
3. Fontan Procedure  

Looking Ahead

Being actively involved in your child's care plan can help you feel more in control.

• Take things one day at a time.
• Look to your care team to guide you on caring for your child, getting ready for surgery, recovery, and more. If you have questions, ask.
• Learn from others. Find a support group for families dealing with a heart problem or talk to other parents whose kids have had heart surgery. Support groups include:
  • the National Pediatric Cardiology Quality Improvement Collaborative (NPCQJC) 
    
  • Sisters By Heart
    
  • the Pediatric Congenital Heart Association (PCHA)  
• Accept help when you can, and lean on those around you for support.
• Keep a journal to record your questions for the medical team.
• Partner with your care team to face the challenges ahead.

The expert teams in our Nemours Cardiac Center locations offer a full range of pediatric heart care to diagnose and treat hypoplastic left heart syndrome. Services vary by specialist and location, but may include:

• Fetal Diagnostics. Early detection in our perinatology and fetal medicine centers help us diagnose congenital heart defects and make a treatment plan for when your baby’s born. 
• Cardiac Diagnostic Testing. State-of-the-art, noninvasive and minimally invasive tests for kids of all ages. 
• Cardiology. Medicines are used to help manage oxygen and blood flow. 
• Cardiac Catheterization. Most babies with HLHS are also born with an atrial septal defect (or “ASD”), but it might be repaired using a catheter (thin, flexible tube) to help relieve symptoms. 
• Heart Surgery. Surgical repair for hypoplastic left heart syndrome will be done in a series that includes the Norwood, Glenn and Fontan procedures. 
• The Nemours app . You can use the app to record vital statistics and provide videos of your child’s progress. The Nemours app is also our patient portal, and includes great features like: 
  • see appointment information
  • message your child's care team 
  • get test results
  • have video visits with your child's providers

Regional HLHS Highlights 

Services, programs, facilities and care teams differ at each location. Call for details.

Sometimes the best support and peace of mind comes from families who’ve been there. Meet some of the inspiring kids we’ve been honored to treat.

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