Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Cardiac Arrest ?
    ### Response:
    The heart has an internal electrical system that controls the rhythm of the heartbeat. Problems can cause abnormal heart rhythms, called arrhythmias. There are many types of arrhythmia. During an arrhythmia, the heart can beat too fast, too slow, or it can stop beating.
    