Truncus Arteriosus: Everything You Need To Know

As far as birth defects go, discovering your baby has an issue with their heart is one of the most dreaded things to learn from medical staff.

Truncus arteriosus may be rare, but this congenital defect truly packs a punch when it does show up. The silver lining is that it is treatable, and your child can go on to live a normal life.

However, the journey to that point can be a frightening one.

In this article, we’ll explain how you can overcome this challenge and take the essential steps to manage truncus arteriosus.

The Normal Development of the Heart

This condition first occurs during pregnancy when the baby’s heart is under development. For the vast majority of cases, a direct cause is unknown.

By looking at the typical structure of the heart and its function, we can get a deeper understanding of the defects.

A normal human heart has four separate chambers, which circulate the blood:

  • The right atrium is the upper-right chamber. It receives blood that is oxygen-poor from the body, and then delivers the blood to the right ventricle.
  • The right ventricle is the lower-right chamber. It pumps blood through the pulmonary artery, which leads into your lungs where blood is resupplied with fresh oxygen.
  • The left atrium is the upper-left chamber. It receives the newly resupplied, oxygen-rich blood from your lungs and delivers it to the left ventricle.
  • The left ventricle is the lower-left chamber. It pumps the oxygen-rich blood through the aorta, which supplies the rest of the body.

Each chamber has a valve, which acts as the chamber door, opening and closing to control the blood flow, ensuring it only flows in one direction.

Understanding the Impact of Truncus Arteriosus

During fetal growth, all babies will have one large vessel that exits the heart. In normal development, this vessel divides into two separate parts.

Colored heart diagram

One part will become the lower part of the aorta, which is connected to the left ventricle. The other part of the vessel will become the lower part of the pulmonary artery, which is connected to the right ventricle.

The ventricles will also develop a septum, which is like a dividing wall between the two chambers.

Blood that is low in oxygen is transferred to the lungs, whereas blood that is rich in oxygen is pumped around the body.

In babies with truncus arteriosus, that single vessel never fully developed, which means it hasn’t divided into two separate vessels. Also, the two ventricles didn’t fully close.

This leaves a single, large blood vessel coming from the heart, and a large hole between the heart’s two ventricle chambers. This hole is called a ventricular septal defect.

Another common issue is that the valve that controls the flow of blood to the single vessel is defective. This allows blood to flow backwards into your heart.

Because of these defects, the two blood types become mixed together, which causes severe problems with circulation.

Without medical treatment, this condition will most likely result in death.

Key Symptoms of Truncus Arteriosus

Purple colored hands

The initial symptoms of this condition are present and obvious within the first days of a baby’s life. Here’s what to look out for:

  • Skin is bluish in color (cyanosis)
  • Pounding heart
  • Poor feeding
  • Excessive sleepiness
  • Shortness of breath or rapid breathing
  • Poor growth

If you notice that your baby is exhibiting any of these symptoms, particularly cyanosis or excessive sleepiness, then seek immediate medical attention.

What Are the Common Risk Factors?

As this is a congenital condition, it is difficult to pinpoint an exact cause of truncus arteriosus. That being said, there are some factors that may increase the likelihood of a heart condition in a newborn baby.

Man smoking a cigarette

These factors include:

  • A viral illness - If an expectant mother gets a viral illness like rubella during the early stages of their pregnancy, it increases the risk of heart defects in the unborn baby.
  • Poorly managed diabetes – It’s important to control your diabetes during pregnancy to lower the chances of any birth defects, including heart problems.
  • Chromosomal disorders – A defective or extra chromosome can cause problems such as DiGeorge's syndrome. Children with such a disorder will also be at higher risk of getting truncus arteriosus.
  • Smoking – It’s never a good idea to smoke, especially while pregnant.

Possible Complications of Truncus Arteriosus

Heart diagram

Due to the abnormalities in the heart’s structures, this condition causes serious circulatory issues. This can cause a range of problems, including:

  • Respiratory trouble – Too much blood will flow into your baby’s lungs. This fluid build-up in the lungs will make it difficult for the child to breathe.
  • High blood pressure – With the increased blood flow going to the lungs, the blood vessels will narrow and the blood pressure in your baby’s lungs will increase. This is known as pulmonary hypertension, and it makes it progressively harder for the baby’s heart to continue pumping blood to the lungs.
  • Cardiomegaly – More commonly known as an enlarged heart. The symptoms above force the heart to work much harder than normal, which causes enlargement. Over time, the heart will gradually get weaker.
  • Heart failure – The combination of complications wears the baby’s heart down, eventually causing the heart to fail completely.

Although surgery during infancy is quite often successful, there is a risk of some heart complications later in life, such as:

  • Leaking heart valves
  • Progressive pulmonary hypertension
  • Irregular heart beat (arrhythmias)

These problems may arise several years later, and the early signs include:

  • Dizziness, fatigue, or shortness of breath during exercise
  • Swelling in the feet or legs
  • Abdominal swelling
  • Heart palpitations

Treatment of Truncus Arteriosus

Medicine in a vial

It is quite rare for a child with truncus arteriosus to survive infancy without undergoing heart surgery. Should such a person survive to adulthood, heart failure is an inevitability, as well as Eisenmenger syndrome.

Usually, sufferers will have multiple surgeries during infancy, with regular follow-ups required as they grow older.

Prior to surgery, certain medications are often prescribed:

  • Diuretics – Sometimes known as “water pills,” these increase the volume and frequency of urination. This is to prevent fluid from building up in the body, staving off the possibility of heart failure.
  • Ionotropic agents – These will strengthen the contractions of the heart.

The first surgery for truncus arteriosus usually happens in the early weeks of life, and typically involves the following procedures:

  • Doctors will use a patch to close the hole between the heart’s ventricle.
  • They will separate the single large vessel to create the upper part of the pulmonary artery.
  • A conduit valve will be implanted so this new pulmonary artery and right ventricle are connected.
  • The single vessel will be reconstructed to form a new aorta.

Can you Prevent Truncus Arteriosus?

For the most part, it’s not possible to prevent congenital heart defects. If your family has a history of heart problems, then the decision to have a child may be one you need to consider carefully with your partner.

Before you do become pregnant, there are some steps that are advised if you want to increase the chances of having a healthy baby.

  • Get a vaccinationBy taking precautions before birth, you can immunize against viruses like rubella to protect your unborn child.
  • Avoid dangerous medication – There are a lot of drugs that shouldn’t be used during your pregnancy. Verify everything with your doctor before you take any medications.
  • Take folic acid – Taking 400mg daily will help combat many birth defects, including congenital heart problems.
  • Control diabetes – Speak with your doctor about the risks related to diabetes when pregnant. By learning how to manage your condition while pregnant, you increase the chances of having a healthy baby.
Doctor writing a medical report

An Early Diagnosis Is Crucial with Truncus Arteriosus

If you believe that your baby may have a heart problem, it’s vital that you seek medical attention immediately.

While there are rare cases of people who live into adulthood without surgery, most babies with truncus arteriosus require medical attention to survive.

At the first sign of any issues such as rapid breathing, excessive sleepiness, or a blue tinge to the skin, take your baby to the hospital. With the right care and treatment, the outlook is good, and your child can grow up and live a happy, fulfilling life.

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