Within seconds of the onset of cardiac arrest, brain function, as evidenced by vital brain stem reflexes, ceases along with the loss of electrical activity. Although a person meets the criteria for death after the heart stops, and organs, including the brain, do not function, the cells of the body do not immediately become irreversibly damaged and “die.” Research has shown that cells in the brain undergo their own process of death that may persist for hours or days after they are deprived of blood flow and oxygen. A landmark study1 in 2001 illustrated this resilience of brain cells, demonstrating that cadaveric human brain biopsy samples taken several hours postmortem had the ability to grow and differentiate in the laboratory.

Stroke treatment offers a valuable analogy for considering the implications of these findings. Stroke occurs when a blood clot blocks blood flow to a region of the brain, and treatment seeks to restore flow before the cells of that region are damaged beyond repair. From the perspective of the brain, cardiac arrest and death are akin to a global stroke of the brain, and much the way that cells in a localized region of the brain can recover following revascularization after stroke, so too are the cells of the whole brain potentially salvageable for some period of time following cardiac arrest.

It is not known exactly when brain cells reach an irreversible state of damage and death—a time when no intervention could stall or reverse the process. However, the revelation that brain cells are more resilient to oxygen deprivation than previously believed presents opportunities to explore interventions that prevent or slow this process long enough for clinicians to address the underlying cause of cardiac arrest and reverse what would otherwise be certain death.

Reference

1. Palmer TD … Gage FH. Progenitor cells from human brain after death. Nature. 2001. DOI. Opens in a new tab.