What Is Hypoplastic Left Heart Syndrome
Hypoplastic left heart syndrome (HLHS) is a rare but serious
birth defect. In HLHS, the left side of your child’s heart is underdeveloped.
This affects the blood flow through their heart.
In a normal heart, the right side pumps blood that needs oxygen
to the lungs, and then the left side pumps blood with fresh oxygen to the bodily
tissues. In HLHS, the left side isn’t able to function. In the first few days
after birth, the right side of the heart can pump blood to both the lungs and
the body. This is possible because of a tunnel-like opening between the two
sides of the heart called ductus arteriosus. However, this opening will
soon close. Then, it becomes difficult for oxygen-rich blood to get to the
HLHS usually requires open-heart surgery or a heart transplant
soon after birth. According to the Centers for Disease
Control and Prevention (CDC), one out of every 4,344 babies born in the
United States has this condition.
What Are the Symptoms of Hypoplastic Left
Since the birth defect occurs while your baby is still in the
womb, most symptoms are apparent immediately after birth. Different areas of
the left side of their heart are affected, so the symptoms will vary depending
on the child.
The common symptoms of HLHS include:
- a blue tinge to their skin, lips, and nails
- a lack of appetite
- dilated pupils
- a vacant stare
- sweaty skin
- mottled skin
- heavy breathing
- rapid breathing
- an increased heart rate
- cold hands and feet
- a weak pulse
What Causes Hypoplastic Left Heart Syndrome?
In most kids, HLHS is related to one of the following:
- a genetic defect
- abnormal chromosomes
- exposure to an environmental toxin
Sometimes, HLHS occurs with no apparent cause.
The following parts of the heart are usually affected by HLHS:
- The mitral
valve controls blood flow between the upper left chamber, or left
atrium, and lower left chamber, or left ventricle, of your child’s heart
- The left
ventricle is the lower left chamber of your child’s heart. It sends
blood to their main artery, or aorta. Their main artery feeds oxygenated blood
to the rest of their body. Underdevelopment of the left ventricle has a major
effect on your child’s life because its strength directly relates to how
effectively oxygenated blood flows through the rest of their body.
- The aortic
valve monitors the flow of blood from your child’s heart into their
aorta is the biggest artery in your child’s body. It’s the primary blood
vessel that leads from their heart to their body.
Babies with HLHS often also have an atrial septal defect. This is
a hole between the upper left and upper right chambers of the heart.
How Is Hypoplastic Left Heart Syndrome
You baby’s doctor will examine them when they’re born to check
for any problems not readily apparent. If your child’s doctor notices any symptoms
of HLHS, they’ll likely want a pediatric heart doctor to examine your baby
Heart murmurs are another physical sign that your child has HLHS.
A heart murmur is an abnormal sound caused by blood flowing improperly. You
child’s doctor can hear this with a stethoscope. In some cases, HLHS is
diagnosed before birth while the mother is undergoing an ultrasound.
The following diagnostic tests may be used as well:
- A chest
X-ray uses radiation to create pictures of your child’s heart.
electrocardiogram measures the electrical activity in your child’s heart.
It will reveal if their heart is beating abnormally, and it will help your
child’s doctor learn if there’s any heart muscle damage.
echocardiogram uses sound waves to create a visual image of the physical
structure and functioning of your child’s heart. The waves will create a moving
picture of their heart and all its valves
- A heart
MRI uses a magnetic field and radio waves to create images of your
How Is Hypoplastic Left Heart Syndrome
Children born with HLHS are usually taken to the neonatal
intensive care unit immediately after birth. Oxygen therapy, such as oxygen through
a ventilator or oxygen mask, will be applied immediately along with
intravenous, or IV, medications to assist their heart and lungs. There are two
major types of surgery to correct their heart’s inability to pump oxygenated
blood back into their body. They two major surgeries are staged heart reconstruction
and a heart transplant.
Staged Heart Reconstruction
The reconstructive surgery is carried out in three stages. The
first stage is right after birth, the next stage occurs when your child is
between 2 and 6 months old, and the last one when your child is between 18
months and 4 years old. The end goal of the surgeries is to reconstruct their
heart so blood can bypass the underdeveloped left side.
The following are the surgical stages of a heart reconstruction:
Stage 1: Norwood Procedure
During the Norwood procedure, your child’s doctor will reconstruct
their heart, including their aorta, by connecting their aorta directly to the
lower right part of their heart. After the surgery, your baby’s skin might
still have a blue tinge. This is because oxygenated blood and deoxygenated
blood are still sharing space in their heart. However, your child’s overall
survival odds will increase if they survive this stage of surgery.
Stage 2: Glenn Shunt
In the second stage, your child’s doctor will begin to reroute the
blood that needs oxygen directly to their lungs instead of through their heart.
Your child’s doctor will reroute the blood using what’s called a Glenn shunt.
Stage 3: Fontan Procedure
During the Fontan
procedure, your child’s doctor completes the rerouting of blood started
in the second stage. At this point, the right chamber of your child’s heart
will only contain oxygen-rich blood and will take charge of pumping this blood
throughout their body. Blood that needs oxygen will flow into their lungs and
then into the right chamber of their heart.
After a staged reconstruction, your baby will be closely
monitored. Their heart is usually left open but covered with a sterile drape.
This is to prevent compression by their rib cage. Several days later, when their
heart has adjusted to its new circulation pattern, their chest will be closed.
If your child gets a heart transplant, they’ll need to take immunosuppressive
medications to prevent rejection for the remainder of their lifetime.
What Is the Long-Term Outlook?
Children with HLHS will require lifelong care. Without medical
intervention in the first few days of life, most infants with HLHS will die.
For most infants, the three-stage surgery is recommended instead of a heart
However, even after the surgeries, a transplant may be needed
later in life. After surgery, your child will need special care and treatment.
Very often, children with HLHS have less physical strength than other children
their age and are slower to develop.
Other long-term effects may include:
- tiring easily when exercising or playing sports
- consistent heart rhythm problems
- a fluid buildup in major parts of their body,
including their lungs, stomach, legs, and feet
- blood clots that could cause a stroke
- abnormal development due to brain and nervous
- a need for follow-up surgeries
It’s recommended that you keep a detailed record of your child’s
medical history. This will be helpful to any doctor your child visits in the
future. Be sure to keep a clear line of open communication with your child so
they can express their feelings and concerns.