Thump, thump, thump… THUD

The human heart beats 2.5 billion times in the course of a typical human lifetime. You rarely have any conscious awareness of this muscle in action, as blood quietly swishes through its chambers. But sometimes a heavy thud comes crashing from the left side of your chest. It may merely mean that you’re nervous or excited. Or it may be a signal of atrial fibrillation.

There are four chambers in your heart: the right and left atria and ventricles. The top chambers, the atria, receive blood returning from your body and lungs. When the electrical system in the atria malfunctions, it causes symptoms that feel like fluttering and sometimes thumping (which are called palpitations). This irregular heart beat is called atrial fibrillation.

Read on to discover more about the symptoms of atrial fibrillation.

A palpitation feels very strange, like something indefinable is wrong in your chest. You may experience a mild fluttering sensation or become suddenly aware that your heart skipped a beat.

It might feel like something alien is going on in your body. “It really felt like I had a fish flopping around in my chest where my heart should be,” says Mellanie True Hills, founder of “It felt like when you are exercising and you can’t breathe. Or palpitations can be subtle. They can feel like butterflies.“

If you could see your heart at the time of your atrial fibrillation, or AFib as many call it, the muscle might remind you more of a nervous rabbit than the strong, self-assured lion it normally is.

The four chambers of the heart normally work in smooth coordination 60 to 100 times a minute to circulate blood throughout your body. The upper atria and the lower ventricles perform a ballet to squeeze efficiently for blood flow. In an atrial fibrillation episode, the atria race or quiver, not allowing the ventricles to fill efficiently.

In addition to palpitations, your atria may send you other signals of distress. These include shortness of breath and chest pain. You may also feel:

  • tired
  • dizzy
  • faint
  • weak
  • confused

Atrial fibrillation can also be asymptomatic. It can turn up during an exam, for instance, or during an electrocardiogram (EKG) set up for another purpose.

If you experience symptoms of atrial fibrillation, talk to your doctor as soon as possible. They will ask about signs of fatigue and lightheadedness. Additionally, they will check your feet and ankles for swelling, as this may indicate heart problems.

Questions your doctor may ask include:

  • Does your chest hurt?
  • Do you have diabetes, high blood pressure, thyroid problems, or heart or lung disease? Do any family members have these disorders?
  • Do any of your family members have atrial fibrillation?
  • Do you smoke, drink alcohol, or use drugs or caffeine?

The frequency of your symptoms will determine how your doctor tests you for atrial fibrillation. If you have chronic, longstanding atrial fibrillation, an EKG can confirm the diagnosis. If you have sporadic events, you may wear a small monitor for up to 48 hours that can capture information about how your heart behaves.

If exercise triggers your atrial fibrillation, you’ll be scheduled for a treadmill test. And if you have very infrequent episodes, you may need to go into a lab for a test that involves catheters and stimulation of the heart (in order to produce erratic behavior).

For the most part, people who turn up in doctors’ offices with atrial fibrillation complained of palpitations. But a 2012 study found that among the elderly, especially those above age 70, atrial fibrillation may be present without the sensation of palpitations.

Emergency responders in the study assessed almost 28,000 people with portable EKG devices. They uncovered atrial fibrillation in nearly 12 percent of emergency medical services patients with suspected heart disease, with typical symptoms decreasing among those who were older.

This disconnect between the upper and lower chambers of the heart leads to inefficient blood flow. Your blood pressure can fall, bringing about the risk of heart failure.

Also, because blood doesn’t empty completely from the atria, dangerous clots may form and break off. If they travel through the ventricle and reach the brain, you could experience a stroke.

Be sure to seek medical care promptly if you experience atrial fibrillation, even if your symptoms are subtle. Feeling faint, for instance, can be enough of a reason to seek help.