Bradycardia is a general term given to an abnormally slow or unsteady heart rhythm, usually less than 50 or 60 beats per minute at rest. It occurs when the electrical impulses controlling normal heartbeat are blocked or otherwise delayed, and can be caused by needle anxiety, or Vasovagal Anxiety Reaction.
Its symptoms include dizziness, fainting, fatigue, and shortness of breath. Bradycardia may be caused by a number of different factors such as age, medication, or pre-existing heart disease. It is largely a condition that is acquired as opposed to being a congenital abnormality.
In controlling bradycardia, symptoms are addressed first and treated accordingly. If no improvement is to be gained, a pacemaker may then be required to regulate heart-rate.