Cardiac arrhythmia (also dysrhythmia) is a term for any of a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. The heart beat may be too fast or too slow, and may be regular or irregular.
Some arrhythmias are life-threatening medical emergencies that can result in cardiac arrest and sudden death. Others cause symptoms such as an abnormal awareness of heart beat (palpitations), and may be merely annoying. Still others may not be associated with any symptoms at all, but predispose toward potentially life-threatening stroke or embolus.
Some arrhythmias are very minor and can be regarded as normal variants. In fact, most people will sometimes feel their heart skip a beat, or give an occasional extra strong beat neither of these is usually a cause for alarm.
The term sinus arrhythmia refers to a normal phenomenon of mild acceleration and slowing of the heart rate that occurs with breathing in and out. It is usually quite pronounced in children, and steadily decreases with age. This can also be present during meditation breathing exercises that involve deep inhaling and breath holding patterns.