Ventricular fibrillation is always diagnosed in an emergency situation. If sudden cardiac death has occurred, a pulse check will reveal no pulse.

Tests to diagnose and determine the cause of ventricular fibrillation include:

  • Electrocardiogram (ECG or EKG). This quick and painless test measures the electrical activity of the heart. Sticky patches (electrodes) are placed on the chest and sometimes the arms and legs. Wires connect the electrodes to a computer, which displays the test results. An ECG can show if the heart is beating too fast or too slowly. If you're having an episode of ventricular fibrillation, the ECG usually shows a heartbeat of about 300 to 400 beats a minute.
  • Blood tests. Blood tests can be done to check for proteins (enzymes) that leak into the bloodstream when the heart is damaged by a heart attack.
  • Chest X-ray. An X-ray image of the chest can show the size and shape of the heart and its blood vessels.
  • Echocardiogram. This noninvasive test uses sound waves to create images of the heart in motion. It can show the heart's size and structure.
  • Coronary catheterization (angiogram). This test helps health care providers see blockages in the heart arteries. A long, thin flexible tube (catheter) is inserted in a blood vessel, usually in the groin or wrist, and guided to the heart. Dye flows through the catheter to arteries in the heart. The dye helps the arteries show up more clearly on X-ray images and video.
  • Cardiac computerized tomography (CT). A CT scan uses X-rays to create cross-sectional images of specific parts of your body.
  • Cardiac magnetic resonance imaging (MRI). This test uses a magnetic field and computer-generated radio waves to create detailed images of blood flow in the heart.
Oct. 28, 2022
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