Cardiac arrest occurs when:

Cardiac arrest occurs when the heart's electrical and mechanical systems malfunction, which leads to the heart being unable to pump blood effectively. This can be due to various reasons, such as arrhythmias (abnormal heart rhythms), which disrupt the normal electrical impulses that control the heartbeat. When this system fails, it results in the cessation of blood flow to vital organs, leading to unconsciousness and a potential fatal outcome if not treated immediately.

While options related to rapid heartbeats or excessive blood loss can lead to serious health complications, they do not directly define cardiac arrest. Rapid heartbeats may not stop the heart entirely but rather create a scenario in which the heart cannot pump effectively. Excessive blood loss can lead to hypovolemic shock but is not a direct cause of cardiac arrest. Similarly, respiratory distress can impact oxygen delivery and may lead to other complications, but it does not specifically result in cardiac arrest if the heart is functioning properly.