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.

Coarctation of the Aorta

What Is Coarctation?

The aorta is the major blood vessel that carries blood away from the heart to the body. When someone has coarctation of the aorta, the aorta is narrowed at some point.

Here's how a healthy heart and aorta work: Blood that needs oxygen comes from all over the body and enters the right side of the heart, which pumps it to the lungs. The lungs fill the blood with oxygen, and this oxygen-rich blood returns from the lungs to the left side of the heart. The left side of the heart finishes up by pumping the blood out through the aorta. From the aorta, the blood travels through arteries that reach all of the body's organs and tissues, bringing them oxygen. Then the blood returns to the heart through veins and begins the cycle once again.

When part of the aorta is narrowed (this is a coarctation), that defect can affect the body's blood circulation because the left side of the heart has to work harder to pump blood through the narrowed aorta.

Sometimes the narrowing is minor and might not even cause symptoms. In other cases, the aorta is more constricted, placing a strain on the heart's left ventricle (the chamber that pumps blood to the aorta and out to the body).

A coarctation can occur anywhere in the aorta, but most often is found after the point where the arteries that carry blood to the upper body and head branch off from the aorta.

Causes

Coarctation of the aorta (or COA) is a congenital defect, meaning that someone is born with it. About 1 in 100 children is born with a heart problem, and coarctation represents about 8% of those cases. Doctors don't know for sure why certain people are born with this narrowing of the aorta.

Coarctation occurs more commonly in boys, but is often seen in girls with Turner syndrome, in which one of two X chromosomes is incomplete or missing. COA may occur with other birth defects or congenital heart conditions, such as a ventricular septal defect (a hole in the wall between the heart's left and right ventricles).

Coarctation also can be associated with other structures abnormalities of the left side of the heart. A common association is a bicuspid aortic valve, in which the aortic valve between the left ventricle and aorta has two leaflets instead of the normal three.

Most people with COA are diagnosed as babies or young children, although some aren't diagnosed until they're teens or even adults. Usually, in this case, the narrowing in the aorta is not severe enough to cause serious symptoms while the person is very young. But even those who do not have major symptoms usually need to be treated because the coarctation can eventually cause problems. COA will not go away on its own.

Signs and Symptoms

Often an abnormal blood pressure test is the first detected sign of COA. During a physical exam, a doctor may find that a child with a coarctation has a higher blood pressure in the arms than in the legs, and also might hear a heart murmur or notice that the pulse in the groin is weak or difficult to feel. Any person diagnosed with high blood pressure should be checked for coarctation of the aorta.

Kids who have COA often do not have any symptoms and have only mild signs that are discovered by accident during a regular visit to the doctor. A child who does have symptoms may experience some or all of these:

  • cold legs and feet
  • shortness of breath, especially when exercising
  • chest pain

Diagnosis and Treatment

Doctors may refer a child with the signs or symptoms of COA to a pediatric cardiologist (a doctor who specializes in diagnosing and treating heart disease in kids and teens). The cardiologist will listen to the heart, feel the pulses, and check blood pressure.

The doctor probably will order an echocardiogram, a test that uses sound waves to create a picture of the heart and its circulation. Other tests that produce images of the heart, such as a chest X-ray, a magnetic resonance imaging (MRI) test, or a computerized tomography (CT) scan, also may be used to help the cardiologist look for a narrowing of the aorta.

A severe coarctation is usually diagnosed shortly after birth and repaired by surgery immediately. In an older patient, doctors often recommend that COA be treated quickly, since it can cause persistent high blood pressure and cause heart enlargement. The defect can also cause dissection or rupture of the aorta, which can be fatal in many people by the age of 40.

Coarctation of the aorta can be repaired either by surgery or other procedures. Different types of surgery can repair a narrowing of the aorta, but one of the most common ways to fix COA is to remove the narrow section and reconnect the two ends of the aorta.

In some cases, doctors may do a procedure known as balloon dilation or balloon angioplasty. They insert a tiny balloon into a blood vessel in the leg and use a very thin wire to thread it up to the aorta, across the narrow area. When the doctor inflates the balloon, the narrow area is expanded. After the area has been widened, the balloon is removed. The cardiologist also may implant a device called a stent to keep the area open after the procedure.

Home Care

Once the defect has been fixed, most symptoms of COA disappear right away because the blockage that caused those symptoms is now gone. Some people will still have high blood pressure for a while and might have to take medicine to control it.

Kids and teens who have had surgery often feel completely better after a week or two, and those who have had the balloon treatment feel better even sooner, often within a couple of days.

But doctors recommend that all patients avoid some physical activities — especially lifting heavy objects or sports that could cause an impact to the chest — for several weeks or months to give the body enough time to heal. Someone whose blood pressure remains high may have to continue to limit certain activities as long as the blood pressure remains high.

Kids who've had a COA corrected will still need to be monitored over time. In some, the narrowing of the aorta can return after surgery or balloon dilation treatment. Regular visits to a cardiologist — often every year or two after recovery — let the doctor monitor blood pressure and look for signs that COA could be returning.

If your child has COA or has had a coarctation repaired, call the doctor if you see shortness of breath, chest pain, or fainting.

Overall, kids who have had coarctation of the aorta can expect to lead a normal life after treatment.

Reviewed by: Steven B. Ritz, MD
Date reviewed: May 2013