Transposition of The Great Arteries

What is Transposition of The Great Arteries?

In this congenital heart defect, the aorta and the pulmonary artery - known as the great vessels - are reversed from their normal positions.The aorta arises from the right ventricle, and the pulmonary artery from the left ventricle. This arrangement produces two circulatory systems (pulmonary and systemic). Oxygenated blood entering the left side of the heart returns to the lungs by the transposed pulmonary artery. Unoxygenated blood entering the right side of the heart returns to systemic circulation by the transposed aorta.

The two circulatory systems communicate somewhat only because of additional cardiac defects. In infants who have a condition called isolated transposition, oxygenated and unoxygenated blood mix slightly at the patent foramen ovale and the patent ductus arteriosus. In infants with other cardiac defects, blood may mix to a greater degree.

Transposition accounts for up to 5% of all congenital heart defects and commonly coexists with other congenital heart defects, such as a ventricular septal defect with or without pulmonic stenosis, an atrial septal defect, and patent ductus arteriosus. Transposition is two to three times more common in males than in females.

Causes of Transposition of The Great Arteries

Transposition of the great arteries results from faulty embryonic development, but the cause is unknown.

Signs & Symptoms of Transposition of The Great Arteries

• Blueness of the skin
• Shortness of breath
• Cool, clammy skin
• Rapid heart rate
• Poor feeding
• Lack of appetite
• Clubbing of the fingers or toes
• Poor weight gain

Diagnostic Tests

Chest X-rays are normal in the first days after birth. Within days or weeks, however, right atrial and right ventricular enlargement cause the heart to take on a characteristic egg shape. X-rays also reveal a narrow mediastinum and increased pulmonary vascular markings except when the infant also has pulmonic stenosis.

Electrocardiogram. An electrocardiogram records the electrical activity in the heart each time it contracts. During this procedure, patches with wires (electrodes) are placed on your baby's chest, wrists and ankles. The electrodes measure electrical activity, which is recorded on paper.

Cardiac categorization reveals decreased oxygen saturation in left ventricular blood and aortic blood: increased right atrial, right ventricular, and pulmonary artery oxygen saturation; and right ventricular systolic pressure equal to systemic pressure. Dye injection shows the transposed arteries and any other cardiac defects.

Arterial blood gas (ABG) measurements indicate hypoxia and secondary metabolic acidosis.

Treatment

An infant with transposition of the great arteries may undergo atrial balloon expository (Rash kind procedure) during cardiac categorization. This procedure enlarges the patent foramen ova le, which improves oxygenation by allowing more of the pulmonary and systemic blood to mix. Afterward, dioxin and diuretics can reduce the degree of heart failure until the infant can withstand corrective surgery (usually before age 1).

The most effective way to correct transposition is through surgery. In the Mustard procedure the atrial septum is replaced with a Dacron or pericardial partition or baffle that channels systemic venous blood to the pulmonary artery. The pulmonary artery then carries the blood to the lungs for oxygenation. Oxygenated blood returning to the heart is channeled into arota.In the Sinning procedure, the same result is accomplished by using the atrial septum to create partitions that redirect blood flow. In the arterial switch, or Antoine procedure, the transposed arteries are anatomized to the correct ventricles.

Prevention Tips

Women who plan to become pregnant should be immunized against rubella if they are not already immune. Good nutrition, avoiding alcohol, and control of diabetes both before and during pregnancy may be helpful.