dextro-Transposition of the great arteries d-Transposition of the great arteries, dextro-TGA, or d-TGA, sometimes also referred to as complete transposition of the great arteries, is a cyanotic congenital heart defect in which the primary arteries (the aorta and the pulmonary artery) are transposed.
In segmental analysis, this condition is described as ventriculoarterial discordance with atrioventricular concordance, or just ventriculoarterial discordance.
d-TGA is often referred to simply as transposition of the great arteries however, TGA is a more general term which may also refer to levo-transposition of the great arteries.
In a normal heart, oxygen-depleted ("blue") blood is pumped from the right side of the heart, through the pulmonary artery, to the lungs where it is oxygenated. The oxygen-rich ("red") blood then returns to the left heart, via the pulmonary veins, and is pumped through the aorta to the rest of the body, including the heart muscle itself.
With d-TGA, blue blood from the right heart is pumped immediately through the aorta and circulated to the body and the heart itself, bypassing the lungs altogether, while the left heart pumps red blood continuously back into the lungs through the pulmonary artery. In effect, two separate "circular" (parallel) circulatory systems are created, rather than the "figure 8" (in series) circulation of a normal cardio-pulmonary system.
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