Is your little one's left heart not developing properly? (Hypoplastic Left Heart Syndrome - HLHS) Let's talk about this!

Today we are going to talk about a slightly complicated, and very rare, but very important heart condition. This is a condition called Hypoplastic Left Heart Syndrome , or (HLHS) for short. You may feel scared when you hear this, but don't worry. Let's talk about this simply, in a way that you can understand. Because, it is very important to be aware of things like this.

What is hypoplastic left heart syndrome (HLHS)?

Simply put, (HLHS) is a congenital heart disease that is present at birth . In this, some parts of the left side of the baby's heart do not develop properly. Think of it like a pump. The left side of this pump is what sends oxygen-rich blood to the whole body. So, when this left side does not develop properly, a problem arises. In this case, these parts of the left side of the heart are mainly affected:

• Left ventricle : This is the main chamber on the lower left side of the heart. It pumps oxygenated blood into the aorta . In HLHS, it is often too small to function properly.
• Aorta : This is the largest blood vessel in our body. It carries blood from the heart to the entire body. In (HLHS), this too may not develop properly.
• Mitral and aortic valves: These are like doors. They only allow blood to flow in one direction. The aortic valve allows blood to flow from the left ventricle into the aorta. The mitral valve allows blood to flow from the upper chamber (atrium) on the left side of the heart to the lower chamber (mitral valve). In HLHS, this valve may not work properly or may be too small.

Sometimes, babies with HLHS may have a small hole in the wall between the two upper chambers of the heart (atrial septal defect) . Normally, this should be a thick wall.

What is the difference between a normal heart and a heart with (HLHS)?

Our normal heart has two sides. The right side pumps deoxygenated blood from the body to the lungs to collect oxygen. Then, the oxygenated blood goes to the left side and is pumped to the rest of the body. However, in a baby with HLHS, the left side of the heart is so small that it can't pump enough blood to the rest of the body. Then, the right ventricle takes over. It tries to pump blood to the lungs and the rest of the body. This is done through the ductus arteriosus.Through a special blood vessel called the ductus arteriosus. This (ductus arteriosus) is a blood vessel that every baby has in the womb. It usually closes a few days after birth. But in a baby with (HLHS), if this blood vessel closes, if left untreated, it can be life-threatening. Because the left side is not working, the only way for blood to get to the body is blocked.

How common is (HLHS)?

(HLHS) is a very rare condition. According to statistics in the United States, it affects about one in 3,800 babies born each year. (HLHS) accounts for between 2% and 3% of all congenital heart diseases (CHD). It is more common in boys than girls.

What are the symptoms of a baby with (HLHS)?

Symptoms of a baby with (HLHS) may not appear right away. They may appear within a few hours or days after birth. The main symptoms are:

• Cyanosis : A bluish-gray coloration of the skin, lips, and fingernails. This may appear as a grayish color in babies with darker skin. It may appear as a blue color in babies with lighter skin. This is caused by the body not getting enough oxygen.
• Difficulty breathing : The baby may feel like it's hard to breathe.
• Difficulty drinking milk: The baby may not want to drink milk, or may spit up when drinking milk.
• Lethargy : The baby may appear sleepy and lethargic.
• Rapid heartbeat.
• Sweating , clammy skin, or feeling cold.
• Weak pulse .

If you notice any of these symptoms, it is important to seek medical advice immediately. Don't panic, but act quickly.

What are the causes of (HLHS)?

In most cases, there is no specific cause for HLHS. Sometimes it may be due to genetic factors. Babies with certain gene mutations , such as GJA1 or NKX2-5, are at increased risk of developing HLHS. Also, babies with certain genetic conditions, such as Turner syndrome or Trisomy 18, can develop HLHS.

How is HLHS diagnosed?

Doctors can diagnose HLHS with non-invasive imaging tests. This can be done either during pregnancy or after the baby is born. During pregnancy:

• Prenatal ultrasound : This is a scan usually performed during pregnancy.
• Fetal echocardiogram: This is a special scan that can check for heart problems while the baby is still in the womb.

After the baby is born: Doctors diagnose the condition by observing symptoms and looking at test results. Sometimes, when listening to the baby's heart with a stethoscope, you may hear a heart murmur . This means that the blood is not flowing properly.

What tests are used to diagnose (HLHS)?

• Chest X-ray: This can check the size and shape of the baby's heart and lungs.
• Echocardiogram: This is also an ultrasound test. The internal structures of the heart can be clearly seen.
• Electrocardiogram (EKG/ ECG ): This is used to measure the electrical changes that occur during a heartbeat.
• Pulse oximetry screening: This can determine the amount of oxygen in the baby's blood.

Is there a treatment for (HLHS)?

Yes, there are treatments. First, the baby needs to be given a medicine called prostaglandin . This keeps the ductus arteriosus open. This creates a path for blood to flow through the body. In addition, other medications may be given to help the baby's heart work more efficiently. The baby may also need to be helped to breathe. Then, several surgeries may be performed. These surgeries are used to redirect blood flow to the lungs and body. After these surgeries, the work of the heart is almost entirely transferred to the right ventricle. It is the one that pumps blood to the whole body.

What surgeries are performed for (HLHS)?

Surgeons perform three main procedures: the Norwood procedure , the Glenn procedure , and the Fontan procedure . These procedures are performed in order. 1. Norwood procedure: This procedure is performed within the first two weeks of life for babies with HLHS. In this procedure, surgeons:

• The baby's underdeveloped aorta is reshaped to allow blood to flow to the body.
• A shunt , a small tube, is inserted to divert blood from the right ventricle, either from the aorta, to the pulmonary arteries that lead to the lungs.
• It creates a connection between the upper chambers (atria) of the heart. This helps to supply the body with oxygen-rich blood from the lungs.

2. Bidirectional Glenn shunt operation: For the babyThe second surgery should be done at about 4 to 6 months. During the Glenn surgery:

• The old shunt is being removed.
• A new shunt is inserted and connects the baby's superior vena cava (SVC) (which carries oxygen-poor blood from the upper body to the heart) to the pulmonary artery.
• This shunt reduces the load on the right ventricle, because it allows blood to go directly to the lungs.

3. Fontan procedure: The final procedure is performed between the ages of 18 months and 4 years . This procedure diverts all the blood returning from the body to the lungs, bypassing the heart. During the Fontan procedure:

• The baby's inferior vena cava (IVC) (which carries oxygen-poor blood from the lower body to the heart) connects to the pulmonary artery.

Are there any complications in the treatment?

Yes, some babies can even lose their lives while going from one surgery to another. Also, there can be some problems after each surgery. For example:

• Problems with the right ventricle not working properly.
• Aortic valve leak.
• Liver disease.
• Abnormal heart rhythms.
• Blood clots.
• Infection.
• Difficulty eating.
• Seizures.
• Kidney problems.
• Cardiac arrest.

These are scary things to hear, but doctors will talk to you about these risks and try to provide you with the best treatment possible.

Is a heart transplant a good treatment?

Sometimes, surgeons may recommend a heart transplant instead of performing those three surgeries. However, babies who have had a heart transplant will have to take medication (immune suppressant drugs) for the rest of their lives.

Can HLHS be treated before birth?

It is currently not possible to completely cure HLHS by surgery during pregnancy. However, fetal surgeons can sometimes perform some interventions to prevent some of the adverse effects that may occur in a developing baby with HLHS (e.g., a small aortic valve). But this is only in very special cases.

Can the risk of (HLHS) be reduced?

Since the cause of most cases of HLHS is unknown, it is difficult to say how to completely prevent it. However, it is always important to follow healthy habits during pregnancy:

• Avoiding alcohol and smoking.
• Controlling other medical conditions such as Diabetes Mellitus .
• Eating a healthy diet.
• Taking a prenatal vitamin that contains at least 400 micrograms (400 mcg) of folic acid daily .

If you or your partner has a family history of HLHS, it is a good idea to talk to a genetic counselor before getting pregnant.

If my child has (HLHS), what should I expect?

After treatment for HLHS, your child will need to see a cardiologist at least once a year for the rest of his or her life. This will make sure that his or her heart, lungs, and other organs are working properly. As your child grows older, he or she will need to see a specialist in adult congenital heart disease . Many children with HLHS will need to take heart medications for the rest of their lives. They will also need to take antibiotics before any surgery, including dental surgery. This can reduce the risk of endocarditis (an infection of the inside of the heart).

What is the outlook for (HLHS) status?

If left untreated, HLHS is a condition that can lead to death within days or weeks of birth. With treatment, the outlook depends on the complexity of the heart defect in the baby. Ask your baby's doctor about the risks of each surgery. Some children may have a lifelong reduced ability to exercise. Doctors usually recommend limiting strenuous physical activity, such as competitive sports.

What is the survival rate of babies with (HLHS)?

This is a bit of a sad fact, but it is important to know. Between 20% and 60% of babies with (HLHS) survive the first year of life. After that, the survival rate for the next five, ten, and fifteen years is about 40%. Babies born at a normal birth weight, without being born prematurely, have better outcomes than babies born with low birth weight. One study found that more babies who survived the first year were still alive at age 18.

It's hard to see these statistics. But remember, medical science is improving every day. New treatments, new technologies are coming. So it's important to keep hope alive.

How do I take care of my child?

Children born with this condition can live healthy lives with long-term care from a cardiologist. You can take care of your child by:

• Give your child the influenza (flu) vaccine and the COVID-19 vaccine every year.
• Take your child to see a cardiologist every six months or once a year .
• Give your child the prescribed medicine on time .
• Limit your child's strenuous physical activity , as recommended by your doctor.
• If your child has learning difficulties , help them.

What questions should I ask my doctor?

If your baby has HLHS, you can ask the doctor questions like:

• What are the risks of surgery?
• Are there any complications to watch out for after surgery?
• What medications does my child need? Are there any side effects to those medications?
• How will the condition (HLHS) affect my child's life?
• What follow-up care does my child need after surgery?
• If I have another baby, is there a risk that that baby will also have (HLHS)?

Having a child with HLHS can be a very emotionally draining and lonely experience . When dealing with the stress and uncertainty of your child's heart disease, it's important to find a support group or other place to get emotional support. Staying mentally strong will help you deal with the ups and downs of your child's health.

Take-Home Message

(HLHS) is a serious, congenital heart disease. However, if detected early and treated properly, children have a chance to live a good life. This requires several complex surgeries and long-term medical supervision. The most important thing is to know that you are not alone. Doctors, nurses, and other health workers are there to help you and your child. It is also very important to get support from other parents who have had similar experiences. Don't lose courage. The sacrifices you make for your child are priceless.