Which of the following best defines a stroke?

A stroke is best defined as the death of brain cells due to a lack of blood supply. This definition reflects the medical understanding that a stroke occurs when blood flow to the brain is interrupted or reduced, preventing brain tissue from getting the necessary oxygen and nutrients. This interruption can arise from a blocked artery (ischemic stroke) or a rupture of an artery leading to bleeding in the brain (hemorrhagic stroke). Without adequate blood flow, brain cells begin to die within minutes, leading to the potential for significant neurological damage or even death.

The other definitions presented do not encapsulate the nature of a stroke. Immediate heart stoppage pertains more to a cardiac event rather than a cerebrovascular incident. Risk of heart failure relates to cardiovascular health issues but does not specifically describe a stroke. A slow heart rate, while it can have implications for overall health, does not directly represent what happens during a stroke. Thus, the chosen definition accurately conveys the critical physiological process involved in a stroke event.