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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:

• Tetralogy of Fallot (ToF)
• Total anomalous pulmonary venous connection
• Hypoplastic left heart syndrome (HLHS)
• Transposition of the great arteries (d-TGA)
• Truncus arteriosus (Persistent)
• Tricuspid atresia
• Interrupted aortic arch
• Coarctation of aorta
• Pulmonary atresia (PA)
• Pulmonary stenosis (critical)

[edit] 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 (may cause cyanosis in some cases)
• Double outlet left/right ventricle

When the defect is long standing, pressure can build up in the pulmonary arteries and the shunt can reverse, thus leading to cyanosis. This is called Eisenmenger syndrome.