Congenitally Corrected Transposition Of The Great Arteries

What is congenitally corrected transposition of the great arteries?

Congenitally corrected transposition of the great arteries (CCTGA) is a rare heart defect affecting less than one percent of all people with congenital heart disease (CHD). This means there are only about 5,000 to 10,000 people in the United States with this condition.

In CCTGA, the heart’s pumping chambers (called ventricles) are reversed. The two main arteries that carry blood to the heart are also switched, so the heart is still able to function in a “corrected” way. That’s why the condition is called "congenitally corrected transposition of the great arteries." However, CCTGA is a complex malformation.

In a healthy heart, the left pumping chamber (left ventricle) sends blood to the entire body. The right pumping chamber (right ventricle) pumps blood only a short distance, to the lungs. The left ventricle is stronger than the right; it can work properly for up to 100 years if no other health problems exist. The right ventricle is not as strong.

In CCTGA, the heart twists abnormally while developing in the womb. The ventricles are reversed so that the left ventricle is on the right, and the right ventricle is on the left. This means the stronger left ventricle pumps blood to the lungs and the weaker right ventricle has the harder chore of pumping blood to the entire body.

This means that the right ventricle is working harder than it was designed to. If the right ventricle stops functioning effectively, a person with CCTGA will begin to develop symptoms.

There are several other problems that also occur in many patients with CCTGA. The most common are:

• A ventricular septal defect (VSD), which is a hole between the two pumping chambers of the heart
• Blockage of the blood on the way to the lungs (called pulmonary stenosis)
• An abnormal tricuspid valve that tends to leak
• A blockage in the heart’s electrical conduction system (which controls the heartbeat) that can lead to heart block and may require a pacemaker

Signs and symptoms of CCTGA

People with CCTGA experience a wide variety of symptoms, depending on other problems with the heart. Some newborns with complex forms of CCTGA have low oxygen levels and need care immediately after birth, but there are also healthy adults who can live a normal life for many years without any treatment.

CCTGA can be detected before birth by fetal echocardiography. If there are also problems with the size of the heart chamber or the function of the heart valves, then cardiac care may be needed immediately after birth.

In some cases, when the heart chamber sizes are normal and there are no other defects, CCTGA may not be diagnosed until adolescence or adulthood, when problems develop because of a leaky heart valve, abnormal heartbeat or the inability of the right ventricle to continue the hard work of pumping blood to the entire body.

Symptoms may include fainting or dizziness from heart block, or fatigue, as the heart becomes unable to pump enough blood to the body.