Transposition of the great arteries

thumb|300px| Transposition of great vessels, atrial septal defect and continuous ductus arteriosus Botalli thumb|250px|RTG: transposition of the great arteries

Transposition of the great arteries (TGA) is a congenital defect in which the systemic and pulmonary circulations are divided into two parallel circuits.

The main arteries depart from the inappropriate chambers and thus two closed circuits are formed – the aorta departs from the right ventricle and the pulmonary artery from the left ventricle.


 * Deoxygenated venous blood from the systemic circulation passes through the right atrium, right ventricle, and aorta back into the systemic circulation. Oxygenated blood from the lungs goes through the left atrium, left ventricle, and pulmonary canal back to the lungs.

This defect is compatible with life only in the presence of atrial septal defect, ventricular septal defect or persistent ductus arteriosus. In these cases, mixed blood circulates in the systemic circulation. When a septal defect is present, children are less cyanotic, but develop heart failure and pulmonary hypertension more quickly. The combination of transposition + septal defect + pulmonary stenosis causes cyanosis, but failure or pulmonary hypertension does not occur.

Clinical picture
It is always a critical defect with early manifestations of severe hypoxia. Among the symptoms we include
 * cyanosis,
 * tachypnea,
 * symptoms of severe heart failure ,
 * hyperactive precordium,
 * no murmur is usually heard (except in combination with pulmonary stenosis).

Diagnosis

 * Echocardiography.

Therapy
Maintaining a normal body temperature is very important, hypothermia would worsen the metabolic acidosis caused by hypoxia. Before surgery prostaglandin E1, s administered to improve oxygenation of the systemic circulation by keeping the ductus arteriosus of Botalli open.Atrial balloon septostomy is also performed. During the first 2 weeks of life corrective surgery will then take place :
 * anatomical correction (arterial switch) is the method of choice. We will surgically return the transposed arteries to their place. But it is a very demanding procedure, it also includes the transfer of coronary arteries to the future aorta. It is necessary to perform it in the first days of life. The functional result is excellent, long-term experience is still lacking.
 * Rastelli correction is indicated for transposition with a septal defect and pulmonary stenosis (not suitable for anatomical correction). The septal defect is closed so that the blood from the LV goes to the displaced aorta, and from the RV and pulmonary artery, the path is replaced by a human vascular transplant, which must change during life.
 * functional correction is not performed as much today. The principle is atrial correction (operation according to Mustard or Senning) – the venous inflow into the atria is transferred to the opposite ventricles using tunnels. Blood from the superior and inferior vena cava is directed to the mitral valve and subsequently to the left ventricle and lung, blood from the pulmonary veins is directed to the tricuspid valve and subsequently to the right ventricle and aorta. The anatomy of the heart is transposed (the aorta goes from the RV, the pulmonary artery goes from the LV). It was performed at the age of 3-8 months. The immediate functional result is excellent, but in the long term it is worse. Sometimes there is a loss of sinus rhythm and various arrhythmias that can lead to sudden death. PK function deteriorates and begins to fail (not enough).

Natural course: without surgery it is very unfavorable, most die in the first days of life.

related articles

 * Congenital heart defects
 * Acquired heart defects