Bradycardia

Bradycardia ( /ˌbrædɪˈkɑrdiə/; Greek βραδυκαρδία, bradykardía, "heart slowness"), in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beats/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their hearts. It sometimes results in fainting, shortness of breath, and if severe enough, death.

Trained athletes or young healthy individuals may also have a slow resting heart rate (e.g. professional cyclist Miguel Indurain had a resting heart rate of 28 beats per minute). Resting bradycardia is often considered normal if the individual has no other symptoms such as fatigue, weakness, dizziness, lightheadedness, fainting, chest discomfort, palpitations or shortness of breath associated with it.

The term relative bradycardia is used in explaining a heart rate which, although not actually below 60 beats per minute, is still considered too slow for the individual's current medical condition.