Congenitally Corrected Transposition of the Great Arteries (CCTGA)

What is Congenitally Corrected Transposition of the Great Arteries (CCTGA)?

CCTGA is rare, with the incidence as <1% of all congenital heart defects.

The normal heart has two pumping chambers called ventricles. The left ventricle pumps blood around the body and the right ventricle pumps blood to the lungs. Because the right ventricle only has to send blood as far as the lungs (a much shorter distance than the left ventricle) it pumps at a lower pressure than the left ventricle which has to pump blood all the way around the body.

In embryology, the heart starts out as a simple tube. It then bends in two, creating the right and left sides of the heart. In CCTGA, it folds in the wrong direction meaning that the ventricles are on the wrong sides. The ventricle meant to grow on the right side is on the left. The ventricle meant to grow on the left side is on the right.

This means that the left ventricle, which normally pumps blood at around the body, only pumps blood as far as the lungs. The right ventricle which normally pumps blood to the lungs is now having to pump blood around the body.

The right ventricle is now under pressure to maintain circulation to the rest of the body and this can lead to right sided heart failure.

Right ventricle
Left ventricle
Left atrium
Right atrium

How can it be spotted?

CCTGA is not commonly detected antenatally. In some cases, a diagnosis is made in infancy.

However, it is not unusual for CCTGA to be found later in childhood or adulthood. This is because you can have CCTGA and have no symptoms.

CCTGA is not normally detected at the 20 week anatomy scan. It can be detected by a postnatal echocardiogram, or an MRI scan.

Up to 90% of babies with CCTGA have another cardiac condition and it may be the signs and symptoms of another cardiac condition that leads to the detection and diagnosis of CCTGA. Conduction problems, like heart block, can be common in babies with CCTGA.

Signs and symptoms of heart conditions in newborns are:
• rapid breathing
• fast heart rate
• grunting or very noisy breathing
• nasal flaring
• poor feeding
• bluish skin colour

How can it be treated?

• If CCTGA is isolated, and there are no other cardiac conditions, then there is no immediate treatment required and there will be no need for any cardiac surgery in the neonatal period.
• If CCTGA is known about before birth then the baby should be monitored closely in a neonatal unit and have a postnatal echocardiogram, ECG and Holter monitor.
• If surgery is required, then the baby/child would have what is known as a double switch operation – an atrial switch and an arterial switch. This is to re-route the blood flows.
• The double switch can be done in most cardiac centres and is an effective option for physiologic repair before the age of ten years
• There is a 2% risk of heart block per year of life, with approximately all needing a pacemaker by 50 years old (but may be earlier if complex surgery is needed)

General advice/info for the future

Babies and children with CCTGA (whether surgically treated or not) will need lifelong follow up. Some children/adults may develop arrhythmias and require treatment later in life.

If your baby/child has had heart surgery, they will have a scar down the middle of the chest, and there will be small scars where drain tubes were used, but these will fade over time.