Truncus Arteriosus – Symptoms and Causes

ByJanis Updated

Overview

Truncus arteriosus is a rare congenital heart defect present at birth. This condition features a single large blood vessel leaving the heart instead of the normal two vessels.

The abnormal structure causes oxygen-poor and oxygen-rich blood to mix, reducing the overall oxygen delivered to the body.

Babies with this condition typically have a ventricular septal defectโ€”a hole between the two lower heart chambers. This defect allows blood to flow between the ventricles, further complicating circulation.

The heart must work harder to compensate for these circulatory changes. Blood flow to the lungs usually increases, putting additional strain on the heart and pulmonary system.

This condition is sometimes called common arterial trunk. Without proper medical intervention, truncus arteriosus can lead to serious health complications as the heart struggles to maintain adequate blood flow and oxygenation throughout the body.

Signs and Symptoms

Truncus arteriosus typically shows symptoms within the first few days after birth.

Babies may have bluish or grayish skin color because of low oxygen levels in their blood. They often seem very tired and have trouble staying awake.

Feeding problems are common, which can lead to poor weight gain and growth issues. Parents might notice their baby has a pounding heartbeat. Fast breathing or shortness of breath are also warning signs.

When to Call a Doctor

Contact your healthcare provider if you have concerns about your baby’s feeding habits, sleep patterns, or growth progress.

Seek emergency care immediately if your baby shows:

  • Blue or gray skin color
  • Rapid breathing
  • Shallow breaths
  • Any difficulty breathing

These symptoms require prompt medical attention as they may indicate serious problems with your baby’s heart or oxygen levels.

Causes

The heart has four main chambers that work together. The right upper chamber (right atrium) collects blood without much oxygen from the body.

This blood moves to the right lower chamber (right ventricle), which pumps it to the lungs through the pulmonary artery. In the lungs, the blood picks up oxygen.

The left upper chamber (left atrium) receives this oxygen-rich blood from the lungs. It then flows to the left lower chamber (left ventricle). This powerful chamber pumps the oxygen-filled blood through the aorta to supply the entire body.

The heart has valves that make sure blood flows in the right direction. These valves open and close with each heartbeat.

During pregnancy, a baby’s heart forms in several complex stages. Early in development, there is one large blood vessel coming from the heart called the truncus arteriosus.

As the baby grows, this single vessel normally divides into two separate vessels:

  • One part becomes the lower portion of the aorta
  • The other becomes the lower section of the pulmonary artery

At the same time, a wall forms between the lower heart chambers. When this development happens correctly, the heart can properly separate oxygen-rich and oxygen-poor blood.

In some babies, however, this process doesn’t complete normally. The truncus arteriosus fails to divide, and a hole remains between the lower heart chambers (called a ventricular septal defect).

Many babies with this condition also have problems with the valve controlling blood flow from the heart to the single vessel. This valve might not close properly, allowing blood to flow backward into the heartโ€”a problem called truncal valve regurgitation.

The exact cause isn’t always clear, but both genetic factors and environmental influences during pregnancy may contribute to this heart development issue.

Risk Factors

Several factors may increase the chance of a baby developing a heart defect at birth:

  • Pregnancy Infections: Certain viral illnesses during pregnancy can affect heart development. For example, contracting German measles (rubella) while pregnant may cause heart abnormalities in the developing baby.
  • Diabetes During Pregnancy: Women with poorly controlled blood sugar levels face a higher risk of having a baby with heart problems. It’s important to work with healthcare providers to manage diabetes before and during pregnancy.
  • Medications: Some prescription and over-the-counter medicines taken during pregnancy can affect heart formation. Always discuss all medications with your doctor if you’re pregnant or planning to become pregnant.
  • Genetic Factors: Chromosomal abnormalities like DiGeorge syndrome (22q11.2 deletion syndrome) and velocardiofacial syndrome increase the risk of heart defects.
  • Smoking: Tobacco use during pregnancy raises the risk of heart conditions in babies. Quitting smoking is strongly recommended for pregnant women.
  • Alcohol Consumption: Drinking alcohol while pregnant can lead to heart problems and other health issues in the developing baby.
  • Maternal Obesity: Being significantly overweight before and during pregnancy increases the chance of having a baby with heart defects.

Health Risks

Truncus arteriosus is a rare heart defect that normally requires surgery in infancy. Adults with this condition face unique challenges.

In very rare instances, individuals with truncus arteriosus may survive to adulthood without surgical repair. However, these cases almost always involve serious complications. The heart must work much harder than normal, which leads to several problems.

Most adults with unrepaired truncus arteriosus develop heart failure. In this condition, the heart cannot pump enough blood to meet the body’s needs. Common signs include:

  • Extreme fatigue
  • Shortness of breath, especially during activity
  • Swelling in the legs, feet, and abdomen
  • Dizziness or lightheadedness

Another serious complication is Eisenmenger syndrome. This condition happens when long-term high pressure damages the blood vessels in the lungs. The damage becomes permanent and causes:

  • Reduced oxygen flow to the lungs
  • Blue-tinged skin (cyanosis)
  • Breathing difficulties
  • Limited exercise ability

Prevention

Certain steps can lower the risk of heart defects in newborns. However, some conditions like truncus arteriosus may not be fully preventable. Good prenatal care is essential for all pregnancies.

Family history considerations:

  • Speak with healthcare providers before conception if heart defects run in your family
  • Consider consulting both a genetic counselor and a cardiologist
  • Understand potential risks and get appropriate screening

Key preventive measures during pregnancy:

  1. Get Necessary Vaccines
    • Protection against rubella (German measles) is particularly important
    • Rubella infection during pregnancy can affect heart development
    • Pre-pregnancy blood tests can confirm immunity
  2. Medication Safety
    • Review all medications with your doctor before and during pregnancy
    • Some drugs can harm developing cardiac structures
    • This includes prescription medications, over-the-counter drugs, and supplements
  3. Take Folic Acid Daily
    • Recommended dose: 400 micrograms
    • Primarily known for preventing neural tube defects
    • May also help reduce congenital heart defect risks
    • Usually part of prenatal vitamins
  4. Diabetes Management
    • Work closely with healthcare providers to control blood sugar
    • Poorly managed diabetes increases risk of birth defects
    • Follow specialized care plans for diabetic pregnancies

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Health Writer

Janis's areas of expertise include nutrition, exercise, stress management, and mental health. She is passionate about educating and empowering people to take control of their health and make positive changes that can last a lifetime. Janis believes that small, sustainable changes are the key to long-term success, and she works with her clients to develop personalized plans that fit their individual needs and lifestyles.