near death experience
Near death the brain releases signals that speed up heart demise.istock

Near death experiences speed up the demise of heart function, a study on rats has shown. Researchers from the University of Michigan Medical School have found a surge in brain activity as the heart deteriorates – and, surprisingly, that these signals play a destabilising role in heart function.

Scientists thought that in the moments before death, the body's systems slow down as blood flow ceases. However, the team found the contrary when it comes to brain signalling.

Publishing their findings in the Proceedings of National Academy of Sciences, the authors looked at asphyxia-induced cardiac arrest in rats. They examined the heart and brain during experimental asphyxiation and found an immediate release of more than a dozen neurochemicals and an activation of brain-heart connectivity. After a steep fall of heart rate, the brain signals strongly synchronised with the heart rhythm.

Study author Jimo Borjigin said: "Despite the loss of consciousness and absence of signs of life, internally the brain exhibits sustained, organised activity and increased communication with the heart, which one may guess is an effort to save the heart."

However, findings showed that this increased surge in brain activity instead caused damage to the heart, leading to its demise. It led to ventricular fibrillation – where the lower chambers of the heart quiver, meaning the organ cannot pump blood.

When researchers blocked the brain's outflow of these signals, it delayed ventricular fibrillation – and increased the survival of both the heart and the brain – possibly pointing to a method of treating cardiac arrest patients.

The authors wrote: "We have shown that blocking the brain's autonomic outflow significantly delayed terminal ventricular fibrillation and lengthened the duration of detectable cortical activities despite the continued absence of oxygen.

"These results support the concept that asphyxia activates a brainstorm, which may be targeted to prevent premature death of the heart and the brain."

Borjigin added: "The study suggests that a pharmacological blockade of the brain's electrical connections to the heart during cardiac arrest may improve the chances of survival in cardiac arrest patients."