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Hypoplastic Left Heart Syndrome


In hypoplastic left heart syndrome, the left side of a newborn baby’s heart hasn’t developed completely.

The heart is a muscular organ that pumps blood containing the oxygen and nutrients that the body needs.

The pumping sections of the heart are the right atrium, right ventricle, left atrium, and left ventricle.

In a normal heart, oxygen-poor blood flows from the body through large veins,

called the superior vena cava and inferior vena cava, into the right atrium.

Next, blood moves into the right ventricle, which contracts, sending blood to the lungs through the pulmonary artery.

Blood picks up oxygen in the lungs, and returns through the pulmonary veins to the left atrium,

then moves into the left ventricle.

Finally, the left ventricle contracts, sending oxygen-rich blood to the body through the aorta.

Before birth, the heart doesn’t send blood to the lungs to get oxygen, since the baby is not breathing yet.

Instead, all the oxygen the baby needs passes from the mothers’ blood to the baby through the placenta and umbilical cord.

In addition, blood from the baby’s heart bypasses the lungs in two ways.

One is through a connection between the pulmonary artery and the aorta, called the ductus arteriosus.

The other is through an opening in the wall between the two atria, called the foramen ovale.

These extra openings allow oxygen-rich blood to bypass the baby’s lungs and still circulate through the body.

Normally, within a day or two after birth, both the ductus arteriosus and the foramen ovale close,

forcing the baby’s blood to travel to the lungs to pick up oxygen.

In  hypoplastic left heart syndrome, a newborn baby’s heart has severe birth defects that prevent blood

from flowing normally to the rest of the body. If the body can’t get oxygen and nutrients, it can’t survive.

The left ventricle, which is the main pump, and the aorta, which is the main pipeline, are smaller than normal,

so the baby’s body does not receive enough blood.

If the foramen ovale and ductus arteriosus are allowed to close as they would normally,

blood flow to the body will decrease even more, resulting in a life-threatening situation.

Symptoms of  hypoplastic left heart syndrome include gray or bluish skin color,

and rapid breathing as the baby tries to get more oxygen to the body. Without surgical intervention, this condition is fatal.

Surgeons will perform three separate operations to treat hypoplastic left heart syndrome.

The goal of these operations is to improve the flow of oxygen-rich blood to the baby’s body.

The Stage One operation, called the Norwood procedure, is performed during the first week after birth.

During the operation, the surgeon will make three main changes.

First, the pulmonary artery will be separated from the right and left pulmonary arteries and connected to the aorta.

A small piece of tubing, called a graft, will be inserted to connect a branch of the aorta and the right pulmonary artery.

Finally, the surgeon will remove the wall between the right and left atria.

These changes increase the flow of oxygen-rich blood from the lungs through both atria into the right ventricle,  

increase the blood flow to the body through the new aorta, and increase the blood flow to the lungs through the graft.

The Stage two operation, called the Glenn procedure, is performed about six months later, when the baby is stronger.

The surgeon will remove the graft connecting the branch of the aorta and the right pulmonary artery.

To replace the graft’s function, the surgeon will disconnect the superior vena cava from the heart

and reconnect it to the right pulmonary artery.

This connection allows oxygen-poor blood from the head and arms to go directly to the lungs to pick up oxygen.

The Stage three  operation, called the Fontan procedure, is performed when the baby is eighteen months to three years old.

The surgeon will disconnect the inferior vena cava from the heart and reconnect it to the right pulmonary artery with graft tubing.

This connection allows oxygen-poor blood from the lower body to go directly to the lungs to pick up oxygen.

The Fontan procedure completes the surgical repair of the heart by achieving these goals:

delivery of oxygen-rich blood to the body through the creation of a new, and expanded aorta,

creation of a new path for oxygen-poor blood to reach the lungs,

and prevention of the mixing of oxygen-rich blood and oxygen-poor blood.

These three operations relieve the life-threatening condition caused by hypoplastic left heart syndrome,

but do not restore normal circulation through the heart.

In some cases, a heart transplant may be done if a donor heart is available,

or the changes from the three surgical procedures aren’t working.

After any of these operations, the child may receive blood thinner medication to prevent the formation of blood clots.

Those with heart transplants will also need medication to prevent their body from rejecting the new heart.

The child may need these medications for the rest of their life.