Download for FREE today - special Mnemonics Cheatsheet - so you can be SURE that you have that Must Know information down: bit.ly/nursing-memory Outline The 4 T's T-Tetralogy of Fallot T-Truncus Arteriosus T-Transposition of the Great Vessels T-Tricuspid Atresia Description Cyanotic heart defects are a group of congenital heart defects that result from deoxygenated blood by-passing the lungs and going into systemic circulation. Tetralogy of Fallot includes 4 anatomical abnormalities that are pictured below. Truncus Arteriosus is a condition where the pulmonary trunk and aorta don't properly divide in development. This results in one large vessel carrying mixed blood to the heart, lungs, and systemic circulation. Transportation of the Great Vessels is a condition where vessels are swapped or may be in abnormal positions. Tricuspid Atresia is a condition where there is no tricuspid valve, which leads to an undersized or absent right ventricle.