Tests and diagnosis

By Mayo Clinic Staff

Ventricular fibrillation is always diagnosed in an emergency situation. Your doctors will know if you're in ventricular fibrillation based on results from:

  • Heart monitoring. A heart monitor that will read the electrical impulses that make your heart beat will show that your heart is beating erratically or not at all.
  • Pulse check. In ventricular fibrillation, there will be no pulse.

Tests to diagnose the cause of ventricular fibrillation

To find out what caused your ventricular fibrillation, you'll have additional tests, which can include:

  • Electrocardiogram (ECG). This test records the electrical activity of your heart via electrodes attached to your skin. Impulses are recorded as waves displayed on a monitor or printed on paper. Because injured heart muscle doesn't conduct electrical impulses normally, the ECG may show that a heart attack has occurred or is in progress.
  • Blood tests. Emergency room doctors take samples of your blood to test for the presence of certain heart enzymes that leak into your blood if your heart has been damaged by a heart attack.
  • Chest X-ray. An X-ray image of your chest allows your doctor to check the size and shape of your heart and its blood vessels.
  • Echocardiogram. This test uses sound waves to produce an image of your heart. During an echocardiogram, sound waves are directed at your heart from a transducer, a wand-like device, held on your chest. Processed electronically, the sound waves provide video images of your heart.
  • Coronary catheterization (angiogram). To determine if your coronary arteries are narrowed or blocked, a liquid dye is injected through a long, thin tube (catheter) that's fed through an artery, usually in your leg, to the arteries in your heart. The dye makes your arteries become visible on X-ray, revealing areas of blockage.
  • Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI). Although more commonly used to check for heart failure, these tests can diagnose other heart problems. You lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest.

    For a cardiac MRI, you lie on a table inside a long tube-like machine that produces a magnetic field that aligns atomic particles in some of your cells. Radio waves aimed at these aligned particles produce signals that create images of your heart.

Nov. 01, 2014

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