definition of bradycardia
Bradycardia, also known as bradyarrhythmia, is a slow heart rate, defined as a heart rate of under 60 beats per minute (BPM) in adults. Bradycardia typically does not cause symptoms until the rate drops below 50 BPM. When symptomatic, it may cause fatigue, weakness, dizziness, and at very low rates, fainting.