“Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow or irregularly.

Heart arrhythmias (uh-RITH-me-uhs) may feel like a fluttering or racing heart and may be harmless. However, some heart arrhythmias may cause bothersome — sometimes even life-threatening — signs and symptoms.”

MAYO CLINIC