Heart and Blood Conditions

Hypoplastic Left Heart Syndrome

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    • For appointments in Seattle, Bellevue, Everett, Federal Way, Olympia, Tri-Cities and Wenatchee, call 206-987-2515.
    • For appointments in Tacoma and Silverdale, call 253-272-1812.
    • For appointments in Alaska, call 907-339-1945.
    • How to schedule

    If this is a medical emergency, call 911.

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  • Locations +

    • Seattle Children's Main Campus: 206-987-2515
    • Bellevue Clinic and Surgery Center: 425-454-4644
    • Everett: 425-304-6080
    • South Clinic in Federal Way: 253-838-5878
    • Olympia: 360-459-5009
    • South Sound Cardiology Clinics: 253-272-1812
    • Tri-Cities (Richland): 509-946-0976
    • Wenatchee: 509-662-9266
    • Pediatric Cardiology of Alaska: 907-339-1945
    • Seattle Children's doctors provide many cardiac services at regional sites throughout the Pacific Northwest. See our complete list of Heart Center locations.

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    • If you are a provider, fax a New Appointment Request Form (NARF) (PDF) (DOC) to 206-985-3121 or 866-985-3121 (toll-free).
    • No pre-referral work-up is required for most conditions. If you have already done testing such as an EKG, Holter monitor or echocardiogram, please fax this information as well as relevant clinic notes and the NARF to 206-985-3121 or 866-985-3121 (toll-free).
    • Your patient will be seen as quickly as possible by the provider who is the best match for managing the current problem.
    • View our complete Heart Center Referral Information (PDF).

Babies with hypoplastic left heart syndrome (HLHS) need surgery in the first weeks of life. They will have a series of surgeries to redirect blood flow through their heart.

Before surgery, your baby will need medicine (prostaglandin) that keeps the ductus arteriosus (the blood vessel between the pulmonary artery and aorta) open so blood can get to the rest of the body. Your baby may need help breathing or need to be on a breathing machine (ventilator).

HLHS is called a “single-ventricle heart defect” because there is only one pumping chamber in the heart. Single-ventricle defects are some of the most complex heart birth defects.

We provide comprehensive care for children with HLHS through our Single Ventricle Program.

Hypoplastic Left Heart Syndrome Treatment Options


Surgery for HLHS does not give babies normal circulation. However, it may allow their heart to pump blood better to their lungs and the rest of their body.

The surgery is done in 3 stages during the first few years of life:

  • The first stage, called the Norwood procedure, is usually performed in the first weeks of life and is the most complex.
  • The second stage, called the Glenn operation, is usually performed between 4 and 7 months of age.
  • The last stage, the Fontan procedure, is usually performed around 3 to 4 years of age. The exact procedures and timing depend on your child’s condition, including how severe it is.

Stage 1: Norwood Procedure

Stage 1: Norwood Procedure

Reprinted with permission www.heart.org. ©2009, American Heart Association, Inc.

The right ventricle is converted to the main pumping chamber and the aorta is made larger. A synthetic tube, called a Sano shunt, brings blood from the ventricle to the lung arteries. A large hole is created between the two atria to allow blood to pass easily between them.

Stage 2: Bidirectional Glenn Operation

Stage 2: Bidirectional Glenn Operation

Reprinted with permission www.heart.org. ©2009, American Heart Association, Inc.

The superior vena cava drains blood from the arms and head. In the Glenn operation, this vein is connected directly to the pulmonary arteries and the Sano shunt is removed.

Stage 3: Fontan Operation

Stage 3: Fontan Operation

Reprinted with permission www.heart.org. ©2009, American Heart Association, Inc.

In the final surgical stage, a synthetic tube is used to bring blood from the lower body directly into the lungs, bypassing the heart. After this surgery, the blood pumped to the body has full oxygen levels.

The goals of the surgeries are:

  • To create a new aorta that can carry enough blood out to the body and to connect this aorta to the right ventricle.
  • To separate oxygen-rich blood from oxygen-poor blood by:
    • Directing oxygen-poor blood, which comes from the organs and tissues of your child’s body, to blood vessels that go to their lungs, without going into their heart first. The blood picks up oxygen in the lungs.
    • Allowing oxygen-rich blood, which comes from your child’s lungs, to flow into their right ventricle. From there, it can be pumped to the rest of their body.


The heart transplant team at Seattle Children’s performs numerous transplants each year for children with HLHS or other heart problems that cannot be treated with standard medical or surgical treatment. Read more about our heart transplant program.

New Treatments for Hypoplastic Left Heart Syndrome

Some babies may be too small or have other medical problems that increase the risk of the first-stage surgery (Norwood procedure) for HLHS. A less complex procedure, called the hybrid procedure, combines surgery and cardiac catheterization. This may be a better option for these higher-risk newborns.

Using a catheter, the heart doctor (cardiologist) widens the opening (foramen ovale) between the left and right atria and places a device called a stent in the ductus arteriosus to keep it open. Then the cardiac surgeon places bands on the pulmonary arteries to control the amount of blood flowing to the lungs. This approach allows the baby to grow and get stronger. During the second stage, the Norwood and Glenn surgeries can be done together with lower risk at 4 to 8 months of age.

Follow-up Care for Hypoplastic Left Heart Syndrome

Outcomes for children with HLHS have improved dramatically in the past several decades. However, the period between the first and second surgeries is a particularly vulnerable time for these infants. Children will be cared for through our Single Ventricle Program, which focuses on the care and monitoring of infants with these severe heart problems.

Seattle Children’s is part of a nationwide group of children’s hospitals called the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) dedicated to improving the outcomes and quality of life for children with HLHS. The NPC-QIC provides additional family resources, support and information.

Adult Congenital Heart Disease Program

To meet your child’s long-term healthcare needs, we have a special Adult Congenital Heart Disease Program to transition your child to adult care when they are ready.

Contact Us

Contact the Heart Center at 206-987-2015 for a cardiac referral, a second opinion or more information.