Tests and diagnosis

By Mayo Clinic Staff

Because ventricular fibrillation is a life-threatening condition, it's unlikely you'd be diagnosed at a routine doctor's appointment unless you happened to collapse in the office. 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, your pulse will be difficult to feel or you may not have a pulse.

Tests to diagnose the cause of ventricular fibrillation

After your doctors diagnose and treat ventricular fibrillation, they'll want to know what caused it. You'll have additional tests to find the cause of your ventricular fibrillation, which can include:

  • Electrocardiogram (ECG). This is the first test done to diagnose a heart attack, which is the most common cause of ventricular fibrillation. 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. Certain heart enzymes slowly leak out into your blood if your heart has been damaged by a heart attack. Emergency room doctors take samples of your blood to test for the presence of these enzymes.
  • 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. The sound waves bounce off your heart and are reflected back through your chest wall and processed electronically to provide video images of your heart.
  • Coronary catheterization (angiogram). This test can show if your coronary arteries are narrowed or blocked. A liquid dye is injected into the arteries of your heart through a long, thin tube (catheter) that's fed through an artery, usually in your leg, to the arteries in your heart. As the dye fills your arteries, the arteries become visible on X-ray, revealing areas of blockage.

    Additionally, while the catheter is in position, your doctor may treat the blockage by performing an angioplasty, also known as coronary artery balloon dilation, balloon angioplasty and percutaneous coronary intervention. Angioplasty uses tiny balloons threaded through a blood vessel and into a coronary artery to widen the blocked area. In most cases, a mesh tube (stent) also is placed inside the artery to hold it open more widely and prevent re-narrowing in the future.

  • Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI). Although more commonly used to check for heart failure, these tests can be used to diagnose heart problems. In a cardiac CT scan, 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.

    In a cardiac MRI, you lie on a table inside a long tube-like machine that produces a magnetic field. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to the type of tissue they are. The signals create images of your heart that can help your doctor determine the cause of your ventricular fibrillation.

Nov. 01, 2011

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