Heart arrhythmia, also known as irregular heartbeat, is a condition that affects the normal rhythm of the heart. There are several synonyms for heart arrhythmia, including dysrhythmia, cardiac arrhythmia, and irregular heart rate. These terms can be used interchangeably to describe any disorder that affects the heart's electrical activity. Other synonyms include abnormal heart rhythm, irregular pulse, and heart palpitations. While heart arrhythmias can be harmless, they can also be life-threatening if left untreated. If you experience any symptoms of irregular heartbeat, such as rapid or slow heartbeat, visit a doctor to get a proper diagnosis and treatment.