Cardiac arrest is a medical emergency defined by the abrupt cessation of detectable heartbeat, resulting in the failure of the circulatory system to deliver oxygenated blood to vital organs. This event signifies a profound physiological crisis because, without immediate intervention, the brain and other tissues are deprived of necessary blood flow, leading to irreversible damage if resuscitation is not promptly initiated. The process typically involves underlying cardiac or respiratory conditions that disrupt the normal electrical conduction of the heart, causing the heart muscle to lose its coordinated rhythm and pumping action. Modern life support protocols focus on maintaining oxygenation and circulating blood through artificial means until the underlying cause of the arrest can be identified and corrected.