Key result
Bilateral common carotid artery ligation resulted in 100% mortality in SHRSP rats within 14 hours, compared to 0% in WKY rats, accompanied by a surge in corticocardiac coupling.
Why the study?
Sudden death is an underrecognized consequence of stroke involving disturbed central autonomic control, but the temporal brain-heart electrical interactions after forebrain ischemia were not well understood.
A marked surge of corticocardiac coupling occurs in rats dying from focal cerebral ischemia, suggesting brain-heart electrical coupling could serve as a biomarker for sudden death risk.
Answers are grounded in this paper and cite their sources.
No clinical action warranted from this animal model; leaves open corticocardiac coupling as a sudden-death biomarker pending human validation.
Sudden death is an important but underrecognized 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 the spontaneously hypertensive stroke-prone rat strain (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 nine SHRSP and eight Wistar-Kyoto (WKY) rats. RR interval was 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 h, whereas no mortality was observed in WKY rats. The functionality of both the brain and the heart were significantly altered in SHRSP compared with WKY rats after BCCAL. SHRSP, 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 forebrain ischemia-induced sudden death. NEW & NOTEWORTHY This study demonstrates a marked surge of corticocardiac coupling in rats dying from focal cerebral ischemia, consistent with our earlier data in rats exposed to fatal asphyxia. Since the bidirectional electrical signal coupling (corticocardiac coherence) and communication (corticocardiac connectivity) between the brain and the heart are only identified in dying animals, they could be used as potential biomarkers to predict the risk of sudden death.
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Liu et al. (2019) studied Forebrain cerebral ischemia (n=17). Bilateral common carotid artery ligation (BCCAL) vs. WKY rats was evaluated on Mortality within 14 h. Bilateral common carotid artery ligation resulted in 100% mortality in SHRSP rats within 14 hours, compared to 0% in WKY rats, accompanied by a surge in corticocardiac coupling.
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