Transposition of the Great Arteries – Symptoms and Causes

Overview

Transposition of the great arteries (TGA) is a serious congenital heart defect present at birth. In this condition, the heart’s major arteries are abnormally positioned, resulting in an incorrect pattern of blood flow through the body.

This defect affects the heart’s ability to supply oxygen-rich blood throughout the body, making early medical attention essential. Though rare, TGA is one of the most common cyanotic heart conditions diagnosed in newborns.

Signs and Symptoms

People with transposition of the great arteries (TGA) show symptoms soon after birth.

Babies with this heart defect often have blue-colored skin (cyanosis) because their blood doesn’t have enough oxygen. They may also breathe faster than normal or have trouble breathing.

Other common symptoms include:

• Poor feeding habits
• Slow weight gain
• Heart murmur (unusual sound during heartbeat)
• Extreme tiredness
• Excessive sweating
• Cold hands and feet

Symptoms usually appear within the first hours or days after birth.

When To Contact a Healthcare Provider

Call your doctor or seek emergency care immediately if your newborn:

• Has bluish or grayish skin color
• Breathes rapidly or struggles to breathe
• Shows poor feeding or excessive tiredness
• Seems unusually irritable
• Has cold hands and feet with blue fingernails

Modern surgical techniques have greatly improved outcomes, but prompt medical attention is essential. Don’t delay seeking help if you notice these warning signs in your baby.

Causes

Complete switching of the main arteries happens before birth while the baby’s heart forms. In a normal heart, the aorta connects to the left ventricle, and the pulmonary artery connects to the right ventricle.

In this condition, these connections are reversed. This creates two separate circulation systems rather than one connected pathway.

There are two main types of transposition of the great arteries:

1. D-transposition (D-TGA): The most common form, where:
   • The aorta is connected to the right ventricle
   • The pulmonary artery is connected to the left ventricle
   • Oxygen-poor blood flows to the body
   • Oxygen-rich blood recirculates to the lungs
2. L-transposition (L-TGA): A rarer form, where:
   • The ventricles are also switched (ventricular inversion)
   • The right ventricle works as the main pumping chamber
   • Blood flows in the correct direction despite the abnormal structure
   • Often called “congenitally corrected transposition”

Risk Factors

The exact cause remains unknown. Most cases happen by chance, with no clear genetic link. Some factors that might increase risk include:

• Maternal Age over 40: Older maternal age is linked to a slightly higher risk of certain congenital conditions, including heart defects.
• Maternal Diabetes: Poorly controlled blood sugar during pregnancy can interfere with normal fetal development, including the heart.
• Alcohol Use During Pregnancy: Alcohol can disrupt organ formation and increase the likelihood of structural birth defects.
• Nutritional Deficiencies: Inadequate intake of essential nutrients—particularly in early pregnancy—may raise the risk of abnormal heart development.
• Smoking During Pregnancy: Tobacco exposure reduces oxygen to the fetus and increases the risk of congenital heart disease.
• Certain Medications: Some drugs taken during early pregnancy may impact fetal organ development, especially if not prescribed or monitored.
• Environmental Exposures: Exposure to industrial chemicals or toxins may affect heart formation during fetal development.
• Genetic Predisposition: Although most cases are not inherited, subtle genetic changes may contribute to TGA in some families.
• Family History of Congenital Heart Defects: A close relative with a heart defect may increase the chance of having a child with a similar condition.

This heart defect affects approximately 1 in every 3,500 newborns. Boys are more likely to have this condition than girls.

Complications

Without treatment, TGA can lead to severe complications such as:

• Life-threatening oxygen deprivation
• Organ damage
• Heart failure
• Death in early infancy

In women with TGA who reach adulthood, pregnancy poses unique challenges. Increased blood volume during pregnancy places additional strain on the heart.

Complication risks depend on:

• The type of surgical repair received
• Current heart function
• Presence of arrhythmias
• Use of heart medications

Before planning a pregnancy, women with TGA should be evaluated by a cardiologist. Pregnancy often requires frequent checkups and collaboration between cardiac and obstetric specialists.

Prevention

Currently, medical science cannot prevent this condition from happening. TGA forms during early pregnancy when a baby’s heart is developing.

There are some steps pregnant women can take to reduce the general risks of birth defects. These actions may help overall heart development, though they cannot specifically prevent TGA.

Steps to promote healthy fetal development:

• Get regular prenatal care
• Take prenatal vitamins with folic acid
• Avoid alcohol, tobacco, and recreational drugs
• Manage chronic health conditions like diabetes
• Check with a doctor before taking any medications

Women with family histories of congenital heart defects should consider genetic counseling before pregnancy. This counseling helps understand potential risks.