Transposition of the great arteries (TGA) is an abnormality of the heart vessels that is present at birth, causing congenital heart disease. This is a serious heart defect that usually requires open heart surgery for the baby to survive.
In a normal heart, the main artery of the body, called the aorta, is attached to the left side of the heart. The main lung artery, called the pulmonary artery, is attached to the right side of the heart. In the birth defect known as transposition of the great arteries, these arteries are reversed. When this happens, blood is routed to the wrong places.
Normally, blood with low oxygen levels is sent to the lungs through the main lung artery to get oxygen. Next, this blood is pumped out through the aorta to the rest of the body. In TGA, blood with low oxygen levels is pumped through the aorta to the rest of the body. It is only because there is usually a hole between the two sides, allowing for some mixing of blood, that the infant survives at all.
The average birth weight and size of a newborn with TGA is larger than normal. Symptoms and signs may include: difficulty breathing, rapid breathing, or shortness of breatha bluish color of the skin, called cyanosissigns of congestive heart failure, which can include swelling in the legs and abdomenheart murmurs, which are abnormal heart soundslow oxygen levels in the blood
The cause of TGA is unknown. Male infants are more commonly affected than females. Children born to mothers with diabetes are also at higher risk.
In most cases, nothing can be done to prevent TGA. A pregnant woman who has diabetes may be able to prevent TGA by controlling her blood sugar levels during pregnancy.
Diagnosis begins with the physical exam. A chest X-ray may reveal an abnormally shaped heart. A heart tracing, called an electrocardiogram or ECG, may also be abnormal. The healthcare professional may order an echocardiogram, which uses ultrasound waves to see the beating heart. This test can show most of the defects in the heart and how they affect the heart's function.
A special procedure called a cardiac catheterization may also be done. This procedure involves inserting a tube though the skin and into a blood vessel, usually in the groin. The tube can then be advanced through the blood vessel into the heart. A contrast agent can be injected through the tube and pictures taken while it is inside the heart and main blood vessels. This can help better define the defects in the heart. This procedure also allows tools to be passed through the tube and into the heart. These tools can make special holes in the heart to improve circulation until surgery can be done.
The long-term effects of TGA are related to the exact nature and severity of the heart defects. Children with TGA often have other heart defects. This can make treatment more complicated and reduce the chance of long-term survival. Death is common in those with TGA, especially when severe or complex defects of the heart are present. In those who undergo surgery, congestive heart failure may occur years later and cause disability or even death.
TGA is not contagious and poses no risk to others.
A baby with TGA needs to be treated in a hospital that specializes in the treatment of children with congenital heart disease. Medications are used to help keep the child alive until surgery can be done. Cardiac catheterization may also be used to place a small hole in the heart to improve circulation. This is usually done only to keep the child alive until surgery.
In some cases, open heart surgery may be done hours after birth. In other cases, surgery may be delayed for a few weeks. There are many different types of surgery, depending on the exact heart defects that are present. The goal of surgery is to make the circulation as close to normal as possible.
There are many different medications that may be used before surgery. These may cause allergic reactions, salt imbalances, or kidney damage. Surgery can be complicated by bleeding, infection, reactions to anesthesia, or even death.
The long-term outlook for a child with TGA usually depends on the severity of the heart defects before surgery. Children will need close monitoring after surgery to make sure the heart is functioning well. Heart medications may be needed after surgery. These medications can help the heart pump better or stop irregular heartbeats, called arrhythmias.
A person who has had TGA repaired during infancy should always inform his or her dentist of the fact, so that he or she can receive antibiotics for routine dental procedures. This precaution helps prevent the heart valves from becoming infected during the unavoidable showers of bacteria through the bloodstream that result from dental work.
A child with transposition of the great arteries will need long-term monitoring. It is important for the parents to watch for any return of heart symptoms and report any change in the child's condition to the healthcare professional.
Merck Manual 1999
Current Medical Diagnosis and Treatment 1996
Harrison's Principles of Internal Medicine 1991
Heart Disease: A Textbook of Cardiovascular Medicine, 1980