Cardiac arrest is primarily caused by what physiological failure?

Cardiac arrest occurs when the heart loses its ability to effectively pump blood throughout the body, most commonly due to the failure of the ventricles to contract. The ventricles are the heart's main pumping chambers, responsible for sending oxygenated blood to the body and deoxygenated blood to the lungs. When they fail to contract properly, the flow of blood ceases, leading to a rapid decline in oxygen delivery to vital organs, which can quickly result in death if not addressed immediately.

While maintaining a regular rhythm is crucial for the heart's function, it is the mechanical action of contraction that directly facilitates blood circulation. Other options refer to issues that may affect blood circulation or perfusion but do not intrinsically cause cardiac arrest in the same direct manner as ventricular contraction failure. Thus, understanding that the core issue in cardiac arrest centers on the ventricles' inability to contract highlights the critical physiological processes necessary for maintaining life.