Cyanotic heart disease is a heart defect, present at birth (congenital), that results in low blood oxygen levels. There may be more than one defect. The defect affects the structure or function of the heart or vessels.

Cyanotic heart disease results in abnormal blood flow from the right to the left part of the body. This abnormal blood flow (called right-to-left shunt) causes too little oxygen to move through the blood.

Cynanotic heart disease causes the child's skin to look blue (cyanosis). This bluish color is most often seen on the lips, fingers, and toes, or during exercise. Some heart defects cause major problems immediately after birth, and some cause few, if any, problems until adulthood.

Congenital heart defects that cause cyanosis include:

• Tetralogy of Fallot
• Transposition of the great vessels
• Ebstein's anomaly
• Tricuspid atresia (a deformity of the tricuspid heart valve)
• Total anomalous pulmonary venous return
• Pulmonic stenosis
• Truncus arteriosus
• Hypoplastic left heart syndrome
• Critical pulmonary valvular stenosis
• Coarctation of the aorta
• Interrupted aortic arch
• Pulmonary valve atresia

Most congenital heart diseases affect only to the heart, but some conditions many affect many organs. Not all congenital heart diseases are cyanotic.

Some cyanotic heart diseases are caused by drug use, chemical exposure, or infections (such as rubella) during pregnancy.

Cyanosis may also be caused by lung disease, abnormal forms of hemoglobin (the protein that carries oxygen through the blood), dehydration, and hypoglycemia.

Cyanosis is a sign of Eisenmenger syndrome, a condition that occurs in patients with congenital heart disease. Eisenmenger syndrome occurs as a complication of increased blood flow from the left side of the heart directly to the lungs. This results in severe lung diseases and increased pressures on the right side of the heart.

One symptom is cyanosis, usually seen as a bluish discoloration of the lips, fingers, and toes.

Some children have dyspnea (breathing problems) and adopt a squatting position after physical activity to relieve breathlessness. Others have hypoxic spells, where their bodies are suddenly starved of oxygen. These are characterized by anxiety, hyperventilation, and a sudden increase in cyanosis.

Syncope (fainting) and chest pain may occur.

Other symptoms depend on the specific type of cyanotic heart disease.

Physical examination confirms cyanosis. The child may have clubbed fingers.

The doctor will listen to the heart and lungs with a stethoscope. Abnormal heart sounds, a heart murmur, and lung crackles may be heard.

Tests will vary depending on the cause, but may be extensive and include:

• Chest x-ray   
• Complete blood count (CBC)
• Arterial blood gas
• ECG (echocardiogram)
• Echo-Doppler
• Transesophageal echocardiogram (TEE)
• Nuclear imaging tests
• Cardiac catheterization
• Electrophysiologic study (EPS)