Transposition of the great arteries is the second most common congenital heart defect that causes problems in early infancy. TGA occurs in 5 to 7 percent of all congenital heart defects.Transposition of the great arteries is a congenital (present at birth) heart defect. Due to abnormal development of the fetal heart during the first 8 weeks of pregnancy, the large vessels that take blood away from the heart to the lungs, or to the body, are improperly connected. As Lily’s heart surgeon who was French put it, ‘Ze Lily she has bad plumbing no? I, I am ze best plumber in ze world. I will fix ze Lily for you Leza.’ Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped through the aorta out to the body. In transposition of the great arteries, the aorta is connected to the right ventricle, and the pulmonary artery is connected to the left ventricle – the exact opposite of a normal heart’s anatomy. This is why babies with Transposition of the Great Arteries were commonly called ‘Blue Babies’. Lily was not a pink baby before her surgery, she had a blueish tinge. Other heart defects are often associated with TGA, and they actually may be necessary in order for an infant with transposition of the great arteries to live. An opening in the atrial or ventricular septum will allow blood from one side to mix with blood from another, creating “purple” blood with an oxygen level somewhere in-between that of the oxygen-poor (blue) and the oxygen-rich (red) blood. Patent ductus arteriosus (another type of congenital heart defect) will also allow mixing of oxygen-poor (blue) and oxygen-rich (red) blood through the connection between the aorta and pulmonary artery. The “purple” blood that results from this mixing is beneficial, providing at least smaller amounts of oxygen to the body, if not a normal amount of oxygen.
What causes transposition of the great arteries?
The heart is forming during the first 8 weeks of fetal development. The problem occurs in the middle of these weeks, allowing the aorta and pulmonary artery to be attached to the incorrect chamber. Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families. Most of the time this heart defect occurs sporadically (by chance), with no clear reason for its development. Early detection does save lives. Thankfully, Lily’s condition was found at her first ultrasound. This is why it is so important for women to ‘put the jelly to the belly’ and get regular prenatal ultrasounds. I have to stress this again early detection saves lives. Babies with Transposition of the Great Arteries will undergo surgery to correct the defect within the first 1 to 2 weeks of age. The procedure that accomplishes this is called a “switch,” which roughly describes the surgical process. The surgery is open heart surgery and is quite extensive.
The good news is that following a TGA repair most babies will lead normal lives with minimal complications. They will have to follow up with a cardiologist quite frequently following their release from the hospital, but typically after they are a year old they only need annual visits.