Transposition of the Great Vessels (Arteries)
In transposition of the great vessels, the aorta and pulmonary artery switch their normal positions. The aorta receives the blood from the right ventricle which does not have much oxygen, but it’s carried back to the body without passing through the lungs to receive more oxygen. Similarly, the pulmonary artery receives the high oxygen blood from the left ventricle but carries it back toward the lungs.
Patients with transposition of the great vessels must have surgery early in life to be able to survive. Some infants have a procedure in the cardiac catheterization laboratory to temporarily delay their surgery until they withstand the stress of surgery. The catheterization procedure enlarges the foramen between the right and left upper chambers (the atria) of the heart. This procedure allows the blood mix together so some oxygen-rich and oxygen-poor blood can be pumped to the correct side. This is a temporary measure.
There are two major surgical procedures used to correct the transposition.
- The first is called a tunnel (or Mustard procedure , or Senning procedure). The surgeon creates a tunnel (aka baffle) between the two atria. The tunnel redirects the oxygen enriched blood toward the right ventricle and aorta and the oxygen-poor blood toward the left ventricle and the pulmonary artery. This operation is known as an atrial or venous switch.
- The second type of surgical treatment is called an arterial switch procedure. The pulmonary artery and the aorta are switched back to their normal position. The aorta is attached by the surgeon to the left ventricle, and the pulmonary artery is placed on the right ventricle. The coronary arteries, which carry vital oxygen enriched blood that supplies the heart muscle, must be moved to the new aorta.
Problems That May Occur
Heart Function may deteriorate over time.
Patients that have had a Mustard or Senning operation may experience a significant decline in the heart muscle function or develop heart valve problems. The reason for this decline is that the right ventricle is pumping all of the blood for the entire body not just the lungs . Drugs may be used to improve the heart muscle function, to avoid fluid accumulation (diuretic meds) . Blood pressure control will also usually help. Patients who’ve had an arterial switch operation have less difficulty with heart muscle decline. They still may have valve leakage. The moved coronary arteries may also have problems.Heart Rhythm Problems(Arrhythmias)
People with repaired transposition of the great vessels, are at risk of developing heart rhythm problems. This is most common with the Mustard or Senning procedures. Heart arrhythmias commonly start in the heart’s atria (or upper chambers). The heart rate can be too slow or too fast. When the heart rate is slow, an electronic pacemaker may be needed to speed it up. When the heart rate is too fast, medications may be used to slow it down. A third arrhythmia treatment option is a a cardiac catheterization to study and treat these rhythm problems.Pregnancy problems for Corrected Transposition Patients
Women who have a repaired transposition of the great vessels may be capable of carrying a pregnancy to full term. Pregnancy stresses the heart of the mother in a normal patient. If a patient has serious heart muscle problems or arrhythmias due to the transposition , they may have problems during pregnancy. The mother must talk to a cardiologist who treats patients with congenital heart problems before getting pregnant.
