Diagnosis

Usually, tetralogy of Fallot is diagnosed soon after birth. Your baby's skin may appear blue. A doctor might hear an abnormal whooshing sound (heart murmur) when listening to the baby's heart with a stethoscope.

Tests to diagnose tetralogy of Fallot include:

• Oxygen level measurement (pulse oximetry). A small sensor placed on a finger or toe measures the amount of oxygen in the blood.
• Echocardiogram. An echocardiogram uses sound waves to create pictures of the heart in motion. An echocardiogram can show the structure, placement and function of the heart wall, heart chambers, heart and pulmonary valves, and aorta.
• Electrocardiogram (ECG or EKG). An electrocardiogram records the electrical activity in the heart each time it contracts. During this procedure, sticky patches with wires (electrodes) are placed on the chest, wrists and ankles. The wires connect to a computer, which displays the heart's rhythm. An ECG can help determine if the heart chambers are enlarged and if there's an abnormal heartbeat (arrhythmia).
• Chest X-ray. A chest X-ray can show the structure of the heart and lungs. A common sign of tetralogy of Fallot on an X-ray is a boot-shaped heart, because the right ventricle is enlarged.

• Cardiac catheterization. Doctors may use this test to evaluate the structure of the heart and plan surgical treatment. During this procedure, the doctor inserts a thin, flexible tube (catheter) into a blood vessel, usually in the groin, and guides it to the heart.

  Dye flows through the catheter to make the heart structures easier to see on X-rays. The doctor can measure pressure and oxygen levels in the heart's chambers and blood vessels during the procedure.