8th March 2024

Transposition of Great Arteries

Transposition of the great arteries (TGA) is the second most common cyanotic heart disease, typically presenting in the first week of birth. It occurs with a prevalence of 20-30 in 100,000 live births and is more common in males (2:1). In TGA, the aorta originates from the morphological RV and the pulmonary artery originates from the morphologic LV. 

There are two main classifications: dextro-TGA (D-TGA), where the aorta is anterior and to the right of the pulmonary artery. The aorta arises from the RV and pulmonary artery from the LV.

In levo-TGA (L-TGA), the aorta is anterior but to the left of the pulmonary artery. 

Associated abnormalities include VSD, LVOT obstruction, mitral and tricuspid valve abnormalities and coarctation of the aorta, which can be diagnosed using an echocardiogram. 

Management

TGA operations include the arterial and atrial switch. Arterial switch surgery is used to correct D-TGA and involves moving the pulmonary artery and aorta into their normal positions to achieve ventriculoarterial concordance. 

Where the arterial switch is not possible due to anatomy, the atrial switch is a procedure which involves redirecting the systemic venous return from the vena cava using a conduit (baffle) made from the pericardium to the LV.  

Post-surgery lifelong follow up care with cardiology is needed. Without surgical repair, the condition is incompatible with life; therefore, adult patients who present to specialist cardiology clinics would have undergone surgical correction of TGA. Clinical signs include loud A2; left parasternal heave and holosystolic murmur of the systemic AV valve. There may be symptoms of right/left heart failure and arrhythmias can occur.