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Dr. Sunil Agarwal

What Is Atrial Fibrillation?


Atrial fibrillation (AF or AFib) is the most common irregular heart rhythm that starts in the atria. Instead of the SA node (sinus node) directing the electrical rhythm, many different impulses rapidly fire at once, causing a very fast, chaotic rhythm in the atria. Because the electrical impulses are so fast and chaotic, the atria cannot contract and/or squeeze blood effectively into the ventricle. Instead of the impulse traveling in an orderly fashion through the heart, many impulses begin at the same time and spread through the atria, competing for a chance to travel through the AV node. The AV node limits the number of impulses that travel to the ventricles, but many impulses get through in a fast and disorganized manner. The ventricles contract irregularly, leading to a rapid and irregular heartbeat. The rate of impulses in the atria can range from 300 to 600 beats per minute. There are two types of atrial fibrillation. Paroxysmal is intermittent, meaning it comes and goes and continuous is persistent.

  • Some people live for years with atrial fibrillation without problems. However, atrial fibrillation can lead to future problems:
    • Because the atria are beating rapidly and irregularly, blood does not flow through them as quickly. This makes the blood more likely to clot. If a clot is pumped out of the heart, it can travel to the brain, resulting in a stroke, or to the lungs, causing a pulmonary embolism. People with atrial fibrillation are 5 to 7 times more likely to have a stroke than the general population. Clots can also travel to other parts of the body (kidneys, heart, intestines), and cause other damage.
    • Atrial fibrillation can decrease the heart’s pumping ability. The irregularity can make the heart work less efficiently. In addition, atrial fibrillation that occurs over a long period of time can significantly weaken the heart and lead to heart failure.
    • Atrial fibrillation is associated with an increased risk of stroke, heart failure, and even death.
    • Most common causes
      • After heart surgery
      • Cardiomyopathy
      • Chronic lung disease
      • Congenital heart disease
      • Coronary artery disease
      • Heart failure
      • Heart valve disease
      • Hypertension (high blood pressure)
      • Pulmonary hypertension
    • Less common causes
      • Hyperthyroidism
      • Pericarditis
      • Viral infection
      • In at least 10 percent of the cases, no underlying heart disease is found. In these cases, AF may be related to alcohol or excessive caffeine use, stress, certain drugs, electrolyte or metabolic imbalances, severe infections, or genetic factors. In some cases, no cause can be found.
    • The risk of AF increases with age, particularly after age 60.
  • You may have atrial fibrillation without having any symptoms. If you have symptoms, they may include:
    • Heart palpitations – Sudden pounding, fluttering, or racing sensation in the chest
    • Lack of energy or feeling over-tired
    • Dizziness – Feeling light-headed or faint
    • Chest discomfort – Pain, pressure, or discomfort in the chest
    • Shortness of breath – Having difficulty breathing during normal activities and even at rest
    • The most commonly used tests to diagnose atrial fibrillation include:

      1. Electrocardiogram (ECG or EKG): The ECG draws a picture on graph paper of the electrical impulses traveling through the heart muscle. An EKG provides an electrical “snapshot” of the heart.

      2. For people who have symptoms that come and go, a special monitor may need to be used to “capture” the arrhythmia.

      3. Holter monitor: A small external recorder is worn over a short period of time, usually one to three days. Electrodes (sticky patches) are placed on the skin of your chest. Wires are attached from the electrodes to the monitor. The electrical impulses are continuously recorded and stored in the monitor. After the monitor is removed, a technician uses a computer to analyze the data to evaluate the heart’s rhythm.

      4. Portable event monitor: A monitor that is worn for about a month for patients who have less frequent irregular heartbeat episodes and symptoms. Electrodes (sticky patches) are placed on the skin of your chest. Wires are attached from the electrodes to the monitor. The patient presses a button to activate the monitor when symptoms occur. The device records the electrical activity of the heart for several seconds. The patient then transmits the device’s recorded information over a telephone line to the doctor’s office for evaluation. The portable event monitor is very useful in determining what heart rhythm is causing your symptoms.

      5. Transtelephonic monitor: When you develop symptoms of atrial fibrillation, a strip of your current heart rhythm can be transmitted to your doctor’s office over the telephone, using a monitor with two bracelets or by placing the monitor against your chest wall.