Heart rate variability predicts cell death and inflammatory responses to global cerebral ischemia.

This study examines the relationship between autonomic functioning and neuropathology following cardiac arrest (CA) in mice. Within 24 h of CA, parasympathetic cardiac control, as indexed by high frequency (HF) heart rate variability, rapidly decreases. By day 7 after CA, HF heart rate variability was inversely correlated with neuronal damage and microglial activation in the hippocampus. Thus, by virtue of its sensitivity to central insult, HF heart rate variability may offer an inexpensive, non-invasive method of monitoring neuropathological processes following CA. The inverse linear relationships between heart rate variability and brain damage after CA also may partially explain why low heart rate variability is associated with increased morbidity and mortality in myocardial infarction patients.