A cyanotic heart defect is a group-type of congenital heart defects

Congenital heart defect

A congenital heart defect is a defect in the structure of the heart and great vessels which is present at birth. Many types of heart defects exist, most of which either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal pattern. Other...

 (CHDs). The patient appears blue (cyanotic

Cyanosis

Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...

), due to deoxygenated blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 bypassing the lung

Lung

The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

s and entering the systemic circulation

Systemic circulation

Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...

. This can be caused by right-to-left

Right-to-left shunt

A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles...

 or bidirectional shunting

Shunt (medical)

In medicine, a shunt is a hole or a small passage which moves, or allows movement of fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either biological or mechanical.* Cardiac shunts may be described as...

, or malposition of the great arteries

Great arteries

Great arteries is a term used to refer collectively to the primary arteries of the heart, which include:* Pulmonary artery: the vessel that carries oxygen-depleted blood from the right ventricle to the lungs....

.

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

• Tetralogy of Fallot
  Tetralogy of Fallot
  Tetralogy of Fallot is a congenital heart defect which is classically understood to involve four anatomical abnormalities...
  
   (ToF)
• Total anomalous pulmonary venous connection
  Total anomalous pulmonary venous connection
  Total anomalous pulmonary venous connection , also known as total anomalous pulmonary venous drainage and total anomalous pulmonary venous return , is a rare cyanotic congenital heart defect in which all four pulmonary veins are malpositioned and make anomalous connections to the systemic venous...
  
  
• Hypoplastic left heart syndrome
  Hypoplastic left heart syndrome
  Hypoplastic left heart syndrome , is a rare congenital heart defect in which the left ventricle of the heart is severely underdeveloped.-Causes:...
  
   (HLHS)
• Transposition of the great arteries (d-TGA)
• Truncus arteriosus (Persistent)
  Persistent truncus arteriosus
  Persistent truncus arteriosus , also known as Common arterial trunk, is a rare form of congenital heart disease that presents at birth...
  
  
• Tricuspid atresia
  Tricuspid atresia
  Tricuspid atresia is a form of congenital heart disease whereby there is a complete absence of the tricuspid valve. Therefore, there is an absence of right atrioventricular connection. This leads to a hypoplastic or absent right ventricle....
  
  
• Interrupted aortic arch
  Interrupted aortic arch
  Interrupted aortic arch is a very rare heart defect in which the aorta is not completely developed. There is a gap between the ascending and descending thoracic aorta. Almost all patients also have other cardiac anomalies. Interrupted aortic arch is often associated with DiGeorge...
  
  
• Pulmonary atresia
  Pulmonary atresia
  Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right...
  
   (PA)
• Pulmonary stenosis (critical)
• Eisenmenger syndrome(Reversal of Shunt due to Pulmonary Hypertension) .
• Patent ductus arteriosus
  Patent ductus arteriosus
  Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...
  
   may cause cyanosis in late stage

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
  Atrial septal defect
  Atrial septal defect is a form of congenital heart defect that enables blood flow between the left and right atria via the interatrial septum. The interatrial septum is the tissue that divides the right and left atria...
  
  
• Ventricular septal defect
  Ventricular septal defect
  A ventricular septal defect is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart.The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.The membranous...
  
  
• Coarctation of aorta (may cause cyanosis in some cases)
• Double outlet left/right ventricle