hello thanks for posting here. transposition of great vessels or TGA is a condition where the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle. In our body, the left ventricle supplies oxygenated blood via the aorta to the various organs of the body to provide oxygen for them to function. the right ventricle receives all this deoxygenated blood back from the organs and then pumps it into the lungs through the pulmonary artery to oxygenate the blood again which is then again directed towards the left side of the heart and the cycle continues. in TGA, Since the connections are interchanged, the deoxygenated blood from the right ventricle goes into the aorta and hence the organs of the body receive deoxygenated blood. this leads to symptoms like breathlessness, bluish discoloration of skin, multiorgan dysfunction etc. similarly the oxygenated blood from the lungs goes to the left ventricle and then into the pulmonary artery again into the lung. so body doesnt receive oxygenated blood. when the fetus is inside the mother, there is a connection between the aorta and pulmonary artery which closes after birth . this duct is called ductus arteriosus which helps in mixing of oxygenated and deoxygenated blood when fetus is inside the mother. in infants with TGA, it is necessary to keep this ductus arteriousus (DA) patent so that oxy- and deoxygenated blood can mix and thr infant receives some amount of oxygenated blood. So inorder to keep this duct patent some medications are given till corrective surgery is done. corrective surgeries basically reconnect the connections so as to supply oxygenared blood to organs and deoxygenated to lungs. Also know there are two forms of TGA, corrected and uncorrected. corrected is when there is transposition but left ventricle depsite being connected to pulmonary artery, the pulmonary artery further supplies the body organs. therefore corrected TGAs are normally asymptomatic and dont require surgery. Uncorrected TGAs are symptomatic and usually require corrective surgeries. i hope this solves your queries. It is very confusing initially to understand, I have used the best possible way to explain you. thank you