You're curled up on the couch, finally relaxing after a long day when suddenly, your heart starts racing. You're obviously ...

Your heart beats about 100,000 times a day. Sometimes it beats faster and sometimes more slowly, depending on what you're doing and whether, for instance, you're all worked up about something. So ...

Tachycardia is the medical term for a heart rate over 100 beats per minute (BPM). It can be a sign of emotional distress or anxiety, anemia (low levels of iron in the blood), infections, dehydration, ...