What is congenitally corrected transposition of the great arteries? (CCTGA)
Congenitally corrected transposition of the great arteries (CCTGA) is a one of the rare heart defect ( 0.5 to 1 % of all babies born with heart defects). Anatomically it is like two negative giving rise to positive. In CCTGA, position of both ventricles (pumping chambers) of the heart is reversed. Fortunately, connections of arteries are also reversed. Thus, like in normal heart, impure blood from body goes to lungs and pure blood from lungs goes to body. However, pumping chambers are reversed. The Stronger left ventricle pumps blood into low pressure pulmonary circulation. The Weaker right ventricle pumps blood into body at higher pressure. Right ventricle can not take additional load for long and it tends to fail over period of time which is usually in around third decade onwards. ( Check normal heart for more details) .
There are several problems that also occur in many patients with CCTGA. The most common problems are:
- Aventricular septal defect(VSD): hole in partition of pumping chamber
- Pulmonary stenosis: narrowed valve.
- Tricuspid valve regurgitation : Leaky valve
- Complete heart block : electrical impulse can not pass from upper chamber to lower chambers. Heart rate is abnormally low.
Signs and symptoms of CCTGA
Babies with isolated CCTGA, are symptomatic at birth. They live pretty healthy and uneventful life. They will develop symptoms later in life after right ventricle fails or complete heart block sets in. Neonates with associated anomalies like VSD, PS can become symptomatic any time after birth. There are sick newborns, with low oxygen level, who need care immediately after birth.
Testing and diagnosis
Diagnosis of CCTGA may require some or all of these tests.
- Fetal echo
- 2D Echocardiogram
- Chest X-ray
- Electrocardiogram(ECG): a record of the electrical activity of the heart
- Cardiac MRI:
- Cardiac catheterization:
- Fetal echo: Complex heart defects can be diagnosed in an baby who is in mother’s womb.
Treatment for CCTGA
Treatment for CCTGA varies according to the type and severity of symptoms and associated defects. In some patients, especially those that have no additional heart defects, there may not be a need to do anything.
There are several operations and strategies used in this condition, including:
- CCTGA VSD pulmonary stenosis : Closure of the hole in the heart (VSD) and insertion of a tube (conduit) between the heart and the lungs. The conduit may need to be exchanged at a later date, requiring another operation.
- Complex CCTGA : Single ventricle repair. Leaving the VSD open and repairing the heart as if it had only one pumping chamber (ventricle). This is called a Fontan repair and involves connecting the veins that bring blood without oxygen back to the heart to go directly to the lungs to pick up oxygen, bypassing the heart.
- Double switch operation. The connections between atria and ventricles are reversed. Also, connections between ventricles and great arteries are reversed. Thus left ventricle is pumping into body and right ventricle is pumping into lungs. This is a very complex operation and is usually performed in infants and children. The double switch procedure is very rarely used in adults.
- Pulmonary artery band : This is a palliative procedure where pulmonary artery is narrowed by an external band. It prevents long term heart failure.
Any of the above operations may also have to include replacement of the leaky tricuspid valve with an artificial valve, and insertion of a pacemaker.
Because those operations are complex and difficult, they are best performed in centers with large patient volume, resources and experience, like the Cardiac Center at Children’s Hospital.
Outlook
Because of enormous strides in medicine and technology, today many children born with congenitally corrected transposition of the great arteries go on to lead healthy, productive lives as adults. Outcomes are also better for those born without additional heart defects.
Follow-up care
Congenitally corrected transposition of the great arteries is a complex heart condition. Some related complications begin and can be treated early in childhood, but others develop later in life. CCTGA requires life-long care by a cardiologist experienced in congenital heart disease.