Despite the loss of consciousness and absence of signs of life in case of sudden cardiac arrest, a storm of brain activity erupts as the heart deteriorates and plays a surprising destabilising role in heart function, says research.
This near-death brain signalling may be targeted to help cardiac arrest patients survive, say the team from University of Michigan after analysing lab tests on animals.
"Despite the 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," said senior study author Jimo Borjigin, associate professor of neurology.
However the brain signalling at near-death may, in fact, accelerate cardiac demise. To understand this, the researchers looked at the mechanism by which the heart of a healthy person ceases to function within just a few minutes without oxygen.
They simultaneously examined the heart and brain during experimental asphyxiation and documented an immediate release of more than a dozen neurochemicals, along with an activation of brain-heart connectivity.
Following a steep fall of the heart rate, brain signals strongly synchronised with the heart rhythm, as visualised beat-by-beat using a new technology developed in the Borjigin laboratory called electrocardiomatrix.
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According to the study, blocking the brain's outflow significantly delayed ventricular fibrillation, in which the lower chambers of the heart quiver and the heart cannot pump any blood.
It is the most serious cardiac rhythm disturbance.
"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," Borjigin said.
The findings provide a neurochemical foundation for the surge in brain activity and a brain-heart connectivity that may be targeted to lengthen detectable brain activity, said the study published in the journal PNAS.