Your or your baby's doctor might suspect tetralogy of Fallot if he or she notices you or your baby has blue-tinged skin or a heart murmur — an abnormal whooshing sound caused by turbulent blood flow. Your or your baby's cardiologist will conduct a physical examination and use several tests to confirm the diagnosis.

Tests may include:

  • Echocardiography. Echocardiograms use high-pitched sound waves to produce an image of the heart. Sound waves bounce off the heart and produce moving images that can be viewed on a video screen.

    This test is generally used to diagnose tetralogy of Fallot. It allows your or your baby's doctor to determine if there is a ventricular septal defect and where it's located, if the structure of the pulmonary valve and pulmonary artery is normal, if the right ventricle is functioning properly, if the aorta is positioned properly, and if there are any other heart defects. This test can also help your or your baby's doctor to plan treatment for the condition.

  • Electrocardiogram. An electrocardiogram records the electrical activity in the heart each time it contracts. During this procedure, patches with wires (electrodes) are placed on your or your baby's chest, wrists and ankles. The electrodes measure electrical activity, which is recorded on paper.

    This test helps determine if the right ventricle is enlarged (right ventricular hypertrophy), if the right atrium is enlarged and if the heart rhythm is regular.

  • 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.
  • Oxygen level measurement (pulse oximetry). This test uses a small sensor that can be placed on a finger or toe to measure the amount of oxygen in the blood.
  • Cardiac catheterization. Doctors may use this test to evaluate the structure of the heart and plan surgical treatment. During this procedure, your or your baby's doctor inserts a thin, flexible tube (catheter) into an artery or vein in the arm, groin or neck and threads it up to the heart.

    Your or your baby's doctor injects a dye through the catheter to make the heart structures visible on X-ray pictures. Cardiac catheterization also measures pressure and oxygen levels in the chambers of the heart and in the blood vessels.