Diagnosis

Ventricular fibrillation is always diagnosed in an emergency situation. A pulse check will reveal no pulse if sudden cardiac death occurred.

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 your heart. Sticky patches (electrodes) are placed on your chest and sometimes your arms and legs. Wires connect the electrodes to a computer, which displays the test results. An ECG can show if your heart is beating too fast, too slow or not at all. 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 enzymes that leak into the bloodstream when the heart is 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 noninvasive test uses sound waves to produce images of your heart's size, structure and motion.
• Coronary catheterization (angiogram). To determine if your coronary arteries are narrowed or blocked, a dye is injected through a long, thin tube (catheter) that's inserted through an artery, usually in your groin area, to the heart's arteries. The dye makes your arteries show up more clearly on X-ray, revealing areas of blockage.
• Cardiac computerized tomography (CT). During 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 creates images of your heart and chest.
• 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. During a cardiac MRI, you lie on a table that slides into a long tubelike machine.