When the heart “skips a beat,” from the 2016 Harvard Heart Letter

Heart palpitations — which can feel like the heart is pounding, racing, or has skipped a beat — can be alarming. But in healthy people, they're usually not dangerous, according to the April 2016 Harvard Heart Letter.

In the most literal sense, palpitations are simply a sudden awareness of one's heartbeat, says Dr. William Stevenson, professor of medicine at Harvard-affiliated Brigham and Women's Hospital. The most familiar trigger for palpitations is heavy exercise, such as when a person pedals extra hard to summit the last computerized hill in an indoor cycling class.

Isolated palpitations typically occur when a small rush of adrenaline courses through the body, causing the heart to beat more forcefully than usual. These surges can be generated by a strong emotion, such as excitement, fear, or anger. They also can come on after consuming a stimulant such as caffeine.

Another routine source of palpitations is premature contraction of the atria. When the heart's upper chambers squeeze a fraction of a second earlier than they should, they rest an instant longer afterward to get back to their usual rhythm. This feels like a skipped beat. It is often followed by a noticeably forceful contraction as the ventricles clear out the extra blood they accumulated during the pause. These premature beats are almost always benign, meaning they aren't life-threatening or the sign of a heart attack in the making. "Everyone has a few of these premature beats once in a while, and they tend to increase with age," says Dr. Stevenson.

However, the sensation of abnormal heartbeat can also be a warning sign of a heart rhythm problem. A sustained fast or irregular heart rhythm originating in either the upper or lower chambers can result in distressing symptoms such as lightheadedness, dizziness, or shortness of breath. So anyone who starts having palpitations or irregular heartbeats that they haven't noticed before would be wise to get checked out, says Dr. Stevenson. This is especially important if the palpitations are accompanied by worrisome symptoms such as shortness of breath or chest pain.

Read the full-length article here: Be still, my beating heart