Final answer:
Agonal rhythm is a very irregular rhythm in which the severely impaired heart is only able to generate an occasional beat from its only remaining pacemaker, the ventricle.
Step-by-step explanation:
Agonal rhythm is an irregular rhythm where a failing heart sporadically generates beats from the ventricles. Sinus rhythm, the heart's normal rhythm, can be restored using a cardiac defibrillator or an artificial pacemaker in cases of severe arrhythmias. This can occur during extreme events like cardiac arrest, where the normal pacemaking system of the heart is nonfunctional. The heart's normal rhythm, established by the sinoatrial node, is called sinus rhythm, which can become disrupted leading to life-threatening arrhythmias such as ventricular fibrillation. Treatments for such arrhythmic events include the use of a cardiac defibrillator, which can restore normal rhythm by delivering an electrical shock, or the implantation of an artificial pacemaker that provides electrical stimulation to regulate heartbeats.