Truncus Arteriosus - Causes, Symptoms, Diagnosis, and Management

Introduction:

Truncus arteriosus is a congenital heart disease that is usually present at birth. It is a rare birth defect, also referred to as “cyanotic heart disease,” that is characterized by a septal defect, a single truncal valve, and a common ventricular outflow tract. This results in the mixing of the systemic venous blood and the pulmonary venous blood at the level of septal defects. This results in the desaturation of blood. In layman’s terms, it is also referred to as “a hole in the heart,” which refers to the defects in the ventricular septum between the two chambers of the heart.

What Is the Normal Functioning of the Heart?

• There are four chambers in the human heart. The upper chambers are called the right and left atrium, and the lower chambers are the right and left ventricles.

• The right atrium and the right ventricles are separated by the “tricuspid valves,” which regulate the blood flow between the right atrium and ventricle.

• Similarly, the left atrium and the left ventricles are separated by the “mitral valve,” which regulates the blood flow between the left atrium and ventricle.

• The deoxygenated or oxygen-poor blood from the other parts of the body is collected by the superior and the inferior vena cava and is poured into the right atrium.

• The tricuspid valve opens, and the oxygen-poor blood enters the right ventricle.

• Now the pulmonary valve opens and allows the blood to flow from the right ventricle to the pulmonary artery. This pulmonary artery carries the blood to each lung for purification.

• After the purification from the lungs, the oxygen-rich blood flows into the left atrium through the pulmonary vein.

• The mitral valve opens up, and the blood enters the left ventricle.

• Now the aortic valve opens up and allows the oxygenated blood from the left ventricles to the aorta, where it is supplied to other parts of the body.

What Is Truncus Arteriosus?

Normally, two blood vessels leave the heart. They are:

1. Aorta: Carries the oxygen-rich blood to other parts of the body.

2. Pulmonary Artery: The deoxygenated blood is carried by the pulmonary artery to the lungs for purification.

So having understood the normal functioning of the heart, now it will be easier to understand what truncus arteriosus is. Truncus arteriosus is a condition where, instead of having two blood vessels, the pulmonary artery and the aorta, the baby will have only one blood vessel that leaves the heart. The large blood vessel fails to separate during the developmental stage resulting in a single blood vessel.

How Does Truncus Arteriosus Affect the Baby?

In the case of truncus arteriosus, the oxygenated blood from the aorta and the deoxygenated blood from the pulmonary artery gets mixed and flows to the lungs and other parts of the body.

What Happens When This Condition Is Untreated?

If truncus arteriosus is not treated in the child, then it may result in two problems. They are:

• Too much circulation enters the lungs resulting in fluid accumulation and making it hard to breathe.

• The blood vessels in the lungs become permanently damaged due to increased blood flow for a longer duration. This results in a life-threatening condition called pulmonary hypertension.

What Is the Cause of Truncus Arteriosus to Occur?

The exact cause of truncus arteriosus is unknown. However, when the baby grows inside the mother’s womb (in-utero), normal embryological growth and development occur. Any disturbances during this stage of development, the baby may encounter several health conditions. Similarly,

• If the embryological process fails to create the septal wall or if the single trunk of the large artery fails to divide into the aorta and pulmonary artery, truncus arteriosus occurs.

• It may also be due to genetic mutations with chromosome number 22q11.

• Some children with truncus arteriosus rarely develop a chromosomal disorder called “Digeorge syndrome,” causing developmental delays and immune problems.

What Are the Symptoms of Truncus Arteriosus?

• Bluish discoloration of the skin, known as a cyanosis, is the most common clinical presentation.

• Growth failures or developmental delays.

• Profuse sweating, tiredness, lethargy, excessive sleepiness.

• Breathing difficulties: Rapid breathing (tachypnea), shortness of breath (dyspnea), grunting, and nasal flaring.

• Clubbing of fingers: The condition where the fingertips are widened.

• Heart murmurs are usually heard with a stethoscope.

How Is Truncus Arteriosus Diagnosed?

Commonly truncus arteriosus may be diagnosed during the pregnancy itself; if not, it is diagnosed soon after birth.

• Prenatal Assessments: An ultrasound taken during routine prenatal visits may sometimes detect this condition. If any heart problem is detected, then a fetal echocardiogram should be taken. This produces images of the baby’s heart.

• Pulse Oximetry: It is a painless procedure that monitors the oxygen content in the blood. Soon after birth, this test is done on the newborn. Low levels of oxygen indicate the presence of cardiac problems.

• Electrocardiogram (ECG): It records the electrical activity of the heart.

• Chest X-ray:

  • Echocardiogram: This confirms the presence of truncus arteriosus. The sound waves create the image of the heart.

  • Cardiac Magnetic Resonance Imaging (MRI): It produces a three-dimensional image of the heart, which detects the presence of any abnormalities.

What Are the Risk Factors for Truncus Arteriosus?

There are several factors that might increase the risk of birth defects in babies.

• Viral Infections: There is an increased risk for congenital heart diseases on exposure to certain viral infections, especially rubella or German measles, during pregnancy.

• Obesity: Obsessed pregnant women have greater chances of developing congenital heart diseases in their babies.

• Uncontrolled Diabetes: Poorly controlled diabetes causes several birth defects, including heart problems in the newborn.

• Use of Certain Medications: Some medications are not advised during pregnancy as they can cause serious birth defects and developmental anomalies in newborns.

• Smoking and Alcohol Consumption: Pregnant mothers consuming alcohol and smoking, especially during the first trimester, have increased chances of congenital heart diseases in their babies.

What Are the Complications of the Children With Truncus Arteriosus Face?

If this condition is not treated, the baby can face the following health conditions.

• Abnormal heart rhythm.

• Heart failure.

• Hypertrophy or cardiomegaly (enlargement of the heart).

• Pulmonary hypertension.

• Respiratory problems.

• Stroke.

How Are They Treated?

As soon as the baby is diagnosed with truncus arteriosus, initial stabilization of the baby is required.

• Medications: Loop and Thiazide diuretics are prescribed to control congestive heart failure.

• Surgical Intervention:

• An open heart procedure is performed within the first few weeks of life or before two months by a cardiothoracic surgeon.

• The cardiothoracic surgeon performs a surgical procedure to patch the ventricular septal defects.

• Then, the separation of the two arteries is done. Most often, the truncal vessels are made to the aorta, and a new pulmonary artery is created using a man-made tube (conduit) with an artificial valve.

• Usually, more than one surgery is performed.

• As the artificial tube does not grow like the natural blood vessels, they have to be replaced as the child grows. Sometimes blockages may be present within the tube due to the blood flow that has to be relieved.

• Regular check-ups are advised after the surgery.

What Are the Steps to Be Followed After the Surgery?

• Soon after the successful surgery, the child requires regular lifelong follow-ups with cardiologists.

• The child should take antibiotics before any other surgery or dental procedures to avoid the risk of bacterial endocarditis.

• The child can perform all activities, play and enjoy their lives. They can also take part in sports but avoid heavy exercise.

Conclusion:

Truncus arteriosus is a rare congenital condition that requires early diagnosis and appropriate treatment. In most cases, the surgery has resulted in an excellent prognosis with high survival rates. Wide exposure and knowledge and post-operative care resulted in these high survival rates. However, special care should be taken by the parents of the children undergoing corrective surgery. Regular follow-ups, following a healthy lifestyle, and maintaining a record of the child’s medical report are always important. On a final note, parents need not worry about their child’s health; most children enjoy, play, and lead a normal life like others.