Transposition of the Great Arteries (TGA) By Lee B Beerman, MD, Children's Hospital of Pittsburgh of the University of Pittsburgh School of Medicine Reviewed / Revised Apr 2023 View Patient Education Pathophysiology Symptoms and Signs Diagnosis Treatment Key Points More Information Topic Resources Dextro-transposition of the... Transposition of the Great... Balloon Atrial Septostomy... Arterial Switch Operation Overview of Transposition... Transposition of the great arteries (in this case, dextro-transposition) occurs when the aorta arises directly from the right ventricle and the pulmonary artery arises from the left ventricle, resulting in independent, parallel pulmonary and systemic circulations; oxygenated blood cannot reach the body except through openings connecting the right and left sides of the heart (eg, patent foramen ovale, ventricular septal defect [VSD]).