Great artery transposition is congenital heart disease that occurs by birth. This defect is found in the pulmonary and aorta (main arteries of the heart), which carry the blood out of the heart. It is a severe heart defect, also called TGA. A newborn baby requires immediate surgery or other medications to cure it. This defect happens when the aorta, which usually arises from the left ventricular side of the heart and pumps red blood, comes from the right ventricular side and pumps blue blood. Likewise, a main pulmonary artery, which usually comes from the right ventricle and pumps blue blood, comes from the left side of the heart and pumps red blood.
Occurrence: About 1,153 infants are born with transposition of artery defect each year in the United States (Samrad, 2021). This defect rate is increasing day by day. Every other baby is facing this problem.
Causes: The causes of the transposition of arteries are unknown in infants. Due to changes in Genes and Chromosomes, some babies have this heart defect. This defect is also caused if the mother takes certain medications, drinks alcohol, and follows a lousy lifestyle. This defect usually occurs in males. The defected infants have average weight like healthy infants.
Diagnosis: This defect is treated immediately after the baby’s birth or during the pregnancy as it also causes severe other heart defects. The most common TGA problems are ventricular septal defect, patent ductus arteriosus, and septal defect. The detail is given as follows;
- Ventricular septal Defect: In this defect, newborn babies have a hole in their hearts. This hole divides the lower two walls of the heart, which causes the tightening or contraction of the heart, and blood moves out to the artery.
- Atrial Septal Artery: In this defect, a hole in the heart of the newborn baby divides the upper two walls of the heart. Due to this defect, the blood moves into the artery.
- Patent Ductus Arteriosus: In this defect, the blood carrier between the two main arteries of the heart fails to close because of the transposition of the arteries. This defect happens when the baby is born.
- Diagnosis During pregnancy:
During pregnancy, specific tests of the mother tell the baby’s congenital disabilities and other problems. That’s why the doctor recommends a complete checkup of the mother every month. An ultrasound test shows the transposition of an excellent artery defect in which the baby’s picture is displayed on a monitor. The more detailed ultrasound test is the fetal echocardiogram. This test shows whether the heart is perfectly working or if there is any defect in it.
- Diagnosis after the baby’s birth:
Defects of the baby occur immediately after the birth. Due to this defect, the baby also suffers from other heart problems. The baby has no severe symptoms of atrial septal defect because it does not cause the mixing of blood. The color of the baby changes to bluish color, which is called cyanosis because the blood does not carry enough oxygen. Symptoms of cyanosis are as follows:
- Trouble in breathing
- Low heartbeat rate
- Bluish skin color
- Problem in feeding
- Pounding heart
This heart defect is usually treated immediately after the birth of the baby. There is a screening test to check the baby’s heart defect which shows the deficiencies of the baby and the heart structure. Likewise, the electrocardiogram demonstrates the inaccurate position of the main arteries, which measures irregular blood flow. These medical tests help to check the heart’s working and make a diagnosis of any heart defect. The detail is given below;
- Pulse Oximetry Screening:
This test checks the oxygen level in the newborn baby’s blood. A critical congenital heart defect is a signal of a low level of oxygen. The transposition of great arteries can be detected by pulse oximetry screening.
Transposes of Great Arteries require immediate surgery for all newborn babies. Before surgery, further treatments are done to treat TGA, which helps oxygen-rich blood to leave the body.
Transposes of great arteries are treated with two types of operations which are as follows:
- Arterial Switch Operation: This method is used to treat the transposition of arteries within the first month of the newborn baby, which brings out the average blood circulation through the heart and other body parts. The main aorta and pulmonary artery are shifted to the original place. The pulmonary artery comes from its ventricular right side, and the aorta comes from its left ventricular side.
- Atrial Switch Operation: Usually, the transposition of great arteries is not treated with this method. A hole is created in the heart, and lanes are placed on the left ventricular side. Due to this hole, the poor oxygen level of blood is carried from the right ventricle to the left ventricle. The blood, rich in oxygen, is carried out through a tunnel from the left to the right side of the heart. This operation helps the body treat TGA and blood to move to the lungs and the whole body. This operation leads to severe complications in later life. Medications are needed after surgery to cure heart defects, control blood pressure, get relief from additional fluid in the body and control the heartbeat rate. The pacemaker is also used to treat breathing problems. After the surgery, if the heart defects and transposition of great arteries are not cured, the infant has some severe lifelong complications. Patients with TGA require regular consultation with a cardiologist to check their heart and avoid further complications.
Types: Transposes of great arteries have two types:
- Dextro-transposes of the great arteries (D-TGA): It is also called complete transposes of the great arteries.
- Causes: It is caused by a shortage of blood oxygen level in the human body.
- Symptoms: During pregnancy, after birth, or within the first three weeks, the symptoms of this transposition of arteries are shown. Without treatment, serious complications, as well as death, may occur in the baby.
- Levo-transposes of the great arteries (L-TGA): It is also known as congenitally corrected transposes of arteries. This type is not so common, and its symptoms are not noticed immediately. Its treatment depends on the specific heart defects.
- Symptoms: During pregnancy, when specific routine screening tests are done, signs or symptoms of transposition of great arteries may be detected. After birth, the following are the sign and symptoms of transposition of the great arteries:
- Cyanosis defect (bluish color of the skin)
- Difficulty in breathing
- Low pulse rate
- Loss of appetite
- Immediate weight gain
- Poor feeding
- Rapid heart rate
Complications: Its complications depend on its type.
- Complications in dextro-transposes of great arteries are the following;
- Deficiency of oxygen in tissues: The body’s tissues receive a small amount of oxygen. This complication causes a patient’s death due to mixing a high and a low amount of oxygen in the blood within the body.
- Heart failure: Heart failure is caused by an inability of the heart to pump the adequate amount of blood as required by the body.
- Complications in Levo-transposes of the great arteries are given below;
- Reduce heart pumping function
- Complete heart block
- Heart valve disease
Preventions: If an individual has a family problem of congenital heart defect, it’s essential to take steps to have a healthy pregnancy. Before getting pregnant, start taking folic acid 400 microgram and multivitamins.
Pathophysiology: The following steps are included in the pathophysiology of transposes of the great arteries:
- Systematic or pulmonary circulation functions in parallel rather than in series.
- These circulations cause transposition of the great arteries.
- The oxygenated venous pulmonary blood returns to the left atrium and the left ventricle.
- The pulmonary vascular blood is re-circulated to the left ventricle with the help of an abnormal pulmonary connection.
- A right atrium and right ventricle deoxygenated systematic venous blood returns.
- Systematic circulation is pumped effectively.
- Oxygen supply is deficient in the right and left ventricular and tissues.
- The mixing of deoxygenated and oxygenated blood takes place at an anatomic level which is incompatible with prolonged survival, such as;