A cyanotic heart defect is a group-type of congenital heart defects (CHDs). The patient appears blue (cyanotic), due to deoxygenated blood bypassing the lungs and entering the systemic circulation. This can be caused by right-to-left or bidirectional shunting, or malposition of the great arteries.

Cyanotic heart defects, which account for approximately 25% of all CHDs, include:

• Transposition of the great arteries (d-TGA)
• Tetralogy of Fallot (ToF)
• Tricuspid atresia
• Truncus arteriosus (Persistent)
• Total anomalous pulmonary return
• Hypoplastic left heart syndrome (HLHS)
• Pulmonary atresia (PA)

Non Cyanotic Heart Defects

Non cyanotic heart defects are more common because of higher survival. In these the shunt is initially from left (oxygenated) to right (non oxygenated). These are

• Atrial septal defect
• Ventricular septal defect
• Patent ductus arteriosus and
• Coarctation of aorta
• Double outlet left/right ventricle

When the defect is long standing, the shunt can reverse and lead to cyanosis.