Actually, there is no difference between the two terms/conditions. Cardiac arrhythmia is usually interchanged with dysrhythmia. Arrhythmia is the irregular beating of the heart or what is usually referred by the phrase "my heart skipped a beat."
Arrhythmia can be further classified into two: tachycardia and bradycardia. Tachycardia is the described as a condition wherein your heart beats too fast while too slow heart beats fall as bradycardia.
Some factors which can cause arrhythmia include heart attack, blood chemistry imbalances, and even abnormal hormone levels. It may also be caused by some substances or medicines.
Most common symptoms, apart from the irregular beating of the heart, include lightheadedness, dizziness, chest pain, shortness of breath, paleness, and sweating.
While most arrhythmias are harmless, some can be dangerous or even fatal. Since the heart beat is too slow, too fast, or irregular, it may be a symptom that the heart is not able to pump enough blood to the body. This lasck in blood flow may result to damages to the brain, heart, and other vital organs.
To further understand arrhythmias, consult your doctor.