Background:

1. TGA accounts for approximately 3 percent of all congenital heart disease (CHD) disorders 大動脈轉位約佔3%先天性心臟病
2. Almost 20 percent of all cyanotic CHD defects 20%的發紺性心臟病源自於TGA
3. 80 percent of patients with DiGeorge syndrome(22q11 deletion) 80%TGA伴有DiGeorge syndrome

Physicopathology:

1. Unknown cause 病因未知
2. Risk factors:
   1. Maternal: diabetes, rubella, poor nutrition, alcohol, >40y/o 包含了糖尿病、德國麻疹、營養不良、酗酒、四十歲以上產婦為高風險
3. Abnormal growth and development of the bilateral subarterial conus 和動脈圓錐的異常發育有關
4. Transposition of pulmonary artery and aorta 大動脈與肺動脈轉位
5. Separated to 2 isolated circuit 原本正常的循環系統被分為兩個獨立的循環
6. RA and RV are full of unsaturated oxygen; LA and LV are full of saturated oxygen 造成右心循環充滿缺氧血；而左心循環充滿充氧血(不交流)

Clinical presentation:

1. Asymptom before birth(covered by foramen ovale, ductus arteriousus and ductus venous) 右心室充氧血可藉由軟圓孔、動脈導管以及靜脈導管流至體循環，故少見症狀
2. After birth, to keep alive must have foramen ovale, ductus arteriosus and VSD to keep alive 為了保持胎兒存活，
3. Cyanosis 發紺
4. Congestive heart failure (RV pumps to aorta, too high pressure) 鬱血心心臟病(右心室需打入體循環，作功過大)
5. RV hypertrophy and LV atrophy 作功大而造成右心肥大；而左心萎縮

Treatment and prevention:

1. Prostaglandin therapy(PGE1)(i.v)→maintain ductal patency 給予PGE1維持動脈導管打開
2. Balloon atrial septostomy (cardiac catheterization) 經心導管以氣球擴張
3. Surgical repair
   1. Arterial switch operation (ASO) 手術-動脈置換術

Reference:

1. Uptodate
2. OB images