Surge of Corticocardiac Coupling in SHRSP Rats Exposed to Forebrain Cerebral Ischemia

Abstract

Sudden death is an important but under-recognized consequence of stroke. Acute stroke can disturb central control of autonomic function, and result in cardiac dysfunction and sudden death. Previous study showed that bilateral common carotid artery ligation (BCCAL) in spontaneously hypertensive stroke-prone rats (SHRSP) is a well-established model for forebrain ischemic sudden death. This study aims to investigate the temporal dynamic changes in electrical activities of the brain and heart and functional interactions between the two vital organs following forebrain ischemia. EEG and ECG signals were simultaneously collected from 9 SHRSP and 8 Wistar-Kyoto (WKY) rats. RR interval and cardiac arrhythmias were analyzed to investigate the cardiac response to brain ischemia. EEG power and coherence (CCoh) analysis were conducted to study the cortical response. Corticocardiac coherence (CCCoh) and directional connectivity (CCCon) were analyzed to determine brain-heart connection. Heart rate variability (HRV) was analyzed to evaluate autonomic functionality. BCCAL resulted in 100% mortality in SHRSP within 14 hours, whereas no mortality was observed in WKY. The functionality of both the brain and the heart were significantly altered in SHRSP compared to WKY after BCCAL. SHRSP rats, but not WKY rats, exhibited intermittent surge of CCCoh, which paralleled the elevated CCCon and reduced HRV, following the onset of ischemia until sudden death. Elevated brain-heart coupling invariably associated with the disruption of the autonomic nervous system and the risk of sudden death. This study may improve our understanding of the mechanism of ischemic stroke-induced sudden death.