Definition: Bradycardia simply means a slow heart rate -- specifically, a heart rate slower than 60 beats per minute.
In many cases, bradycardia is normal. Healthy people often have resting heart rates in the 40s and 50s, especially while asleep.
However, if a person has disease in the heart's electrical system, an abnormal bradycardia might occur. Abnormal bradycardias (also called "bradyarrhythmias") are often seen in older people, and can produce weakness, lightheadedness and dizziness, and if severe, can lead to loss of consciousness. This condition can be treated by implantation of a pacemaker.
There are two general causes of abnormal bradycardia: sick sinus syndrome, and heart block.
