Hypoplastic Left Heart Syndrome

Heart With Hypoplastic Left Heart Syndrome

Note: To view heart animations, you need the latest version of the
Adobe Flash Player.


Hypoplasia is defined as underdevelopment of a tissue or organ, usually due to a deficiency in the number of cells. Hypoplastic left heart syndrome is the underdevelopment of the left side of the heart, including the left atrium and ventricle, the mitral valve, the aortic valve, and the aorta.

In some cases an associated ASD allows blood returning from the lungs to flow through the opening in the septum from the left to the right atrium. The mixed blood enters the right ventricle and is then pumped into the pulmonary artery. The blood reaches the aorta through a patent ductus arteriosus, which is kept open by intravenous medication. This heart defect is fatal within the first days or months of life without treatment.

Treatment Options

Options for treatment include a series of three operations collectively known as the Norwood Procedure or heart transplantation. The goal of the Norwood Procedure is to direct deoxygenated blood directly to the lungs and utilize the functional right heart to pump oxygenated blood to the body.

 
Stage I Norwood Procedure

The first stage, performed in the first week of life, is known as the Stage I Norwood Procedure. The connection between the right ventricle and the branch pulmonary arteries is broken and the main pulmonary artery and the small aorta are connected and augmented to create a new, larger aorta. Next, a small tube (shunt) is placed between the aorta and the right branch pulmonary artery to allow for blood flow to the lungs.

Post-Modified Stage I Norwood Procedure

The modified Stage 1 Norwood Procedure connects the Pulmonary artery to the Right Ventricle using a shunt. The underdeveloped Aorta is reconstructed and enlarged.

The right ventricle is converted into a common systemic (to the body) ventricle. The oxygenated and de-oxygenated blood mix in the right atrium and right ventricle and is then dispersed out to the body, through the reconstructed aorta, and to the lungs through the RV to PA shunt and pulmonary artery.

The purpose of the modified Stage 1 Norwood Procedure is to allow blood to circulate in a controlled manner throughout the body, without obstruction.

 
Hemi-Fontan Procedure (Second Stage)

The Hemi-Fontan procedure is the second of three operations for children with hypoplastic left heart syndrome and other types of single ventricle physiology. This procedure is generally performed at 6 months of age. The Hemi-Fontan consists of anastomosis of the superior vena cava (SVC) to the right pulmonary artery, augmentation of the branch pulmonary arteries and patch closure of the communication between the superior vena cava and the right atrium.

After the Hemi-Fontan procedure, the blue blood returning from the upper body through the SVC is immediately diverted to the lungs, without passing through the heart. This blood becomes oxygenated in the lungs and returns to the left atrium. This red or oxygenated blood then passes through the atrial communication into the right atrium. The deoxygenated blood from the lower body enters the right atrium through the inferior vena cava (IVC); there it mixes with the oxygenated blood from lungs. The mixed blood then passes into the right ventricle and is pumped out into the reconstructed aorta to supply the body. The importance of this procedure is that it relieves the single ventricle of having to pump an excess volume of blood. Prior to this procedure, the ventricle is pumping both to the body and to the lungs. Following the Hemi-Fontan, the ventricle pumps only to the body, since the lung is supplied with blood flow directly from the superior vena cava.

 
Third and Final Stage

The third and final stage is performed at approximately 12 months of age. During this procedure, the deoxygenated blood of the lower half of the heart is directed to the lungs. This is done by channeling the blood of the inferior vena cava through the right atrium to the right branch pulmonary artery.


What Is Normal Cardiac Anatomy?

When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

 
Learn More About Normal Cardiac Anatomy

Heart With Normal Cardiac Anatomy

Note: To view heart animations, you need the latest version of the
Adobe Flash Player.


When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

The heart is composed of four chambers. The two upper chambers, known as atria, collect blood as it flows back to the heart. The two lower chambers, known as ventricles, pump blood with each heartbeat to the two main arteries (the pulmonary artery and the aorta). The septum is the wall that divides the heart into right and left sides. The atrial septum separates the right and left atria; likewise, the ventricular septum separates the two ventricles.

There are four valves that control the flow of blood through the heart. These flap-like structures allow blood to flow in only one direction. The tricuspid and mitral valves, also known as the atrioventricular valves, separate the upper and lower chambers of the heart. The aortic and pulmonary valves, also known as the arterial valves, separate the ventricles from the main arteries. Oxygen-depleted blood returns from the body and drains into the right atrium via the superior and inferior vena cavas. The blood in the right atrium then passes through the tricuspid valve and enters the right ventricle.

Next, the blood passes through the pulmonary valve, enters the pulmonary artery, and travels to the lungs where it is replenished with oxygen. The oxygen-rich blood returns to the heart via the pulmonary veins, draining into the left atrium. The blood in the left atrium passes through the bicuspid, or mitral, valve and enters the left ventricle.

Finally, the oxygen-rich blood flows through the aortic valve into the aorta and out to the rest of the body.

Congenital Heart Defects

What Is a Congenital Heart Defect?

A congenital heart defect is a problem in the heart's structure that is there when a baby is born. Heart defects can range from mild to severe.

What Causes a Congenital Heart Defect?

Congenital heart defects happen because of incomplete or abnormal development of the fetus' heart during the very early weeks of pregnancy. Some are known to be associated with genetic disorders, such as Down syndrome.

But the cause of most congenital heart defects isn't known. While they can't be prevented, many treatments are available for the defects and related health problems.

Common Heart Defects

Common types of congenital heart defects, which can affect any part of the heart or its surrounding structures, include:

What Are the Signs & Symptoms of a Heart Defect?

Because congenital defects often affect the heart's ability to pump blood and to deliver oxygen to the tissues of the body, they often produce telltale signs such as:

  • a bluish tinge or color (cyanosis) to the lips, tongue, and/or nailbeds
  • an increased rate of breathing or difficulty breathing
  • poor appetite or difficulty feeding
  • failure to thrive (weight loss or failure to gain weight)
  • abnormal heart murmur
  • sweating, especially during feedings
  • a weaker pulse

If you notice any of these signs in your baby or child, call your doctor right away. If your doctor notices these signs, you may be referred to a pediatric cardiologist (a doctor who specializes in treating heart problems).

How Is a Heart Defect Diagnosed?

Some congenital heart defects cause serious symptoms right at birth. For those, a baby will go to the newborn intensive care unit (NICU) in the hospital for immediate evaluation by a cardiologist. Other defects might not be diagnosed until the teen years — or even adulthood.

Newborn Screening

Newborns in the U.S. are screened at least 24 hours after birth to look for serious congenital heart problems that can lower oxygen levels. This screen is a simple, painless test using a machine called a pulse oximeter. The oximeter uses a sensor put on a baby's skin that estimates how much oxygen is in the baby's blood. This test can help spot heart problems early on so that they can be treated right away. The screening will find most serious heart defects, but some babies who test normal could still have a problem, especially COA or other defects on the left side of the heart.

Testing

After a complete physical exam, including evaluation of the baby's heart rate and blood pressure, the cardiologist will order an electrocardiogram (EKG).

The cardiologist will probably order an echocardiogram — a test that uses sound waves to create a picture of the heart and its circulation. Echocardiograms are the primary tool for diagnosing congenital heart defects.

A fetal echocardiogram is a specialized type of ultrasound that allows diagnosis of heart problems in utero. This can be done as early as 16–18 weeks into the pregnancy. These tests are ordered when a possible heart abnormality is seen on a level II ultrasound. They're also done if another close family member has a congenital heart defect or if the mother has a condition, such as diabetes, that might make a heart problem in the fetus more likely.

Sometimes, doctors order a chest X-ray or a cardiac catheterization.

When Should I Call the Doctor?

If you think your child may have a heart problem or you notice any signs (such as difficulty breathing or feeding, or blue lips or tongue) that concern you, call your doctor. If your baby suddenly turns very blue or loses consciousness, call 911.

More treatments than ever are available for congenital heart defects, and most defects are treated successfully. Children with heart problems are best cared for by a team of specialists, which usually will include:

  • pediatric cardiologists
  • pediatric heart surgeons
  • pediatric cardiac anesthesiologists
  • doctors specialized in the intensive care of children with heart problems and specialized nurses, nurse practitioners, physician assistants, and many others

Many kids with heart problems benefit from having their hearts fixed surgically or through a cardiac catheterization procedure. The sooner they get medical attention, the better the chances for the fullest recovery possible.

With all the medical resources available, a congenital heart defect won't necessarily prevent a child from leading a normal life. By working with the health care team, you'll get the best care possible for your child.

Reviewed by: Steven Dowshen, MD
Date reviewed: October 30, 2017