L-Transposition of Great Arteries - An Overview

Introduction

The heart condition levo-transposition of great arteries is an uncommon disease seen in newborns. In this disorder, the two lower chambers of the heart are interchanged. The left ventricle is on the heart’s right side and gets blood from the upper right chamber. The lower right heart chamber is on the left side and get’s blood from the upper left heart chamber. The blood flow throughout the body is correct, but it can cause trouble to the heart pumping action in the long term.

How Does the Heart Pump Blood?

The pulmonary artery carries blood from the heart to the lungs for oxygenation. The pulmonary artery is connected to the heart’s lower right chamber. The chamber is known as the right ventricle. Followed by the transportation of oxygen-rich blood from the lungs to the core. The oxygen-rich blood gets into the heart’s left upper chamber, the left atrium. The blood is then pushed to the heart’s lower left chamber, the left ventricle. Aorta that forms the main artery is connected to the left ventricle. The artery is responsible for transporting oxygen-rich blood from the heart to the body. In a normal heart, the left ventricle is bigger and stronger than the right.

What Is the L-Transposition of Great Arteries?

L-transposition of great arteries is also known as congenitally corrected transposition. It is a disorder caused by heart malformation resulting in reversed blood flow. The lower left and right chambers are interchanged in this disease, causing this abnormality. This transposition is less severe than other forms as more significant arteries (aorta and pulmonary artery) are reversed. The disorder allows oxygen-rich blood to be supplied to body organs and oxygen-poor blood to reach the lungs. The condition may develop due to genetic factors. However, the exact etiology is unknown.

What Are the Risk Factors for Developing L-Transposition of Great Arteries?

• A history of rubella (viral infection that spreads through contact) or other viral infections during pregnancy increases the risk.

• Taking specific medicines or smoking while pregnant.

• Alcohol consumption during pregnancy.

• Uncontrolled diabetes while pregnant.

These risk factors can increase the risk of developing L-transposition of great arteries.

What Are the L-Transposition Symptoms of Great Arteries Seen in Children and Adults?

A newborn with this congenital disability is often undetected. The anomaly can be hidden until adulthood when congestive heart failure, heart murmur (sound of blood flowing in the heart), and abnormal heart rhythm develop.

The disorder causes the right ventricle to pump blood at a higher pressure than normal. This progressively reduces the right ventricular function resulting in congestive heart failure. Few patients may exhibit heart muscle problems, tricuspid valve leakage, and abnormal heart rhythm. The tricuspid valve may be connected to the right ventricle forming Ebstein’s anomaly. If the ventricular septal defect (hole in the wall between ventricles) and pulmonary valve blockage develops, the newborn may develop blue skin color and heart murmurs. The skin color changes may not be noticeable early as other heart ailments may allow oxygen-rich blood to circulate. However, the blue or gray skin changes become noticeable as the baby becomes more active. Slow heart rhythm and complete heart block are standard features of L-transposition of great arteries. The newborns born with this condition also exhibit weak pulse, loss of appetite, and poor weight gain. Few patients may experience fainting, trouble breathing, and light-headedness.

How Can L-Transposition of Great Arteries Be Diagnosed?

Prenatal diagnosis is possible with a fetal echocardiogram (sound waves are used to form images of the fetal heart). The diagnosis is typically considered when symptoms develop. The tests advised are

• Cardiac catheterization is a procedure in which a thin tube is inserted through a blood vessel to diagnose clogged arteries or treat them.

• Chest X-ray is a standard test to detect heart disease and response to treatment.

• Electrocardiogram (ECG) is a procedure that can measure the heart’s rhythm and electrical activity.

• Cardiac MRI (magnetic resonance imaging) is an imaging procedure that can identify cardiac structure and anomalies.

What Is the Treatment for L-Transposition of Great Arteries?

The patients are prescribed medications to improve heart pumping. In addition, medications control fluid accumulation and blood pressure, which can prevent symptoms of congestive cardiac failure. An individual with very slow heart rhythms is provided with pacemakers. Patients with Ebstein anomaly may require valve replacement. A non-surgical procedure called cardiac catheterization may be necessary for a few patients. Surgery is not needed in patients suffering from this disease.

However, patients with septal defects or pulmonary valve obstruction may require surgery. The surgery is helpful in the closure of heart holes, removal of the blockage in blood flowing to the lungs, and tricuspid valve leakage repair. Patients with severe ventricular defects may require additional complex surgical procedures like a double switch.

The patients may require lifestyle changes like avoidance of weight lifting to prevent elevation of blood pressure.

What Is the Double Switch?

A double switch is a surgical procedure that involves two operations performed at the same time. The first portion of the operation is known as the atrial switch. Depending on the technique used, the surgery is known as a Mustard (procedure for complete correction of transposition with synthetic material use) or Senning operation (operation done with the help of the body’s tissue). In this procedure, there is rechanneling of blood flow from the right atrium to the right ventricle and from the left atrium to the left ventricle.

The second portion of the operation is known as the arterial switch. In this procedure, the aorta and pulmonary artery are disconnected. Followed by switching and reconnecting with the proper ventricle.

What Are the Complications That Can Develop With the L-Transposition of Great Arteries?

• The disorder causes reduced heart pumping as the right lower chamber pumps blood to the whole body. The chamber could be more efficient in pumping as it is not designed for the purpose. This causes changes in the pumping action of the heart.

• The transposition of chambers causes structural changes in the heart that can generate variations in electrical signals. If all the signals are blocked, it can cause complete heart blockage.

• A tricuspid valve that separates the upper and lower chamber can malfunction. It can cause incomplete valve closure causing the blood to move back through the valves. This condition is known as tricuspid valve regurgitation. This condition can gradually decrease the pumping action of the heart.

Conclusion

L-transposition of great arteries is a disorder that can be present in an individual without any symptoms. When diagnosed, the condition must be treated aggressively with medications. Surgery must be performed in required cases. The patient may require lifelong monitoring from a cardiologist.