Type of cyanotic congenital heart disease
Aorta arises from the right ventricle and the pulmonary artery from the left ventricle
Results in two parallel circulations
The first sends deoxygenated systemic venous blood to the right atrium and back to the systemic circulation via the right ventricle and aorta
The second sends oxygenated pulmonary venous blood to the left atrium and back to the lungs via the left ventricle and pulmonary artery
Incompatible with life unless there is communication between the two parallel circuits
Mixing occurs either intracardiac (patent foramen ovale, VSD or ASD) OR extracardiac connections (patent ductus<unk> us or bronchopulmonary collateral circulation)
Often associated with other cardiac abnormalities
Ventricular septal defects (VSD)
Left ventricular outflow tract obstruction (dynamic or anatomical)
Mitral and tricuspid valve abnormalities
Coronary artery variations
Prevalence in the United States is estimated to be 4.7 per 10,000 live births
Accounts for 3% of  all congenital heart disease and almost 20% of all cyanotic CHD defects 
The first sends deoxygenated systemic venous blood to the right atrium and back to the systemic circulation via the right ventricle and aorta
The second sends oxygenated pulmonary venous blood to the left atrium and back to the lungs via the left ventricle and pulmonary artery
Mixing occurs either intracardiac (patent foramen ovale, VSD or ASD) OR extracardiac connections (patent ductus<unk> us or bronchopulmonary collateral circulation)
Ventricular septal defects (VSD)
Left ventricular outflow tract obstruction (dynamic or anatomical)
Mitral and tricuspid valve abnormalities
Coronary artery variations
Transposition of the great arteries
Cyanotic
Total anomalous pulmonary venous return
Tetralogy of fallot
Tetralogy of Fallot
Ebstein anomaly
Tricuspid atresia
Hypoplastic left heart syndrome