Changes and prognosis of coupling between heart and brain in ischemic stroke rats

Abstract

Objective To study the changes of heart-brain coupling indexes after cerebral ischemia in a rat model of middle cerebral artery occlusion (MCAO) and the relationship with prognosis in the early stage. Methods Twenty male SD rats(7~8 weeks old, body weight 290±25 g) were randomly divided into 2 groups (n=10): the cerebral ischemia group (MCAO group) and the control group (Sham group). Lead Ⅱ electrocardiography (ECG) and dual-channel electroencephalogram (EEG) were recorded at the baseline and 0~4 h after the surgery. Neurofunctional recovery was evaluated by neurological deficit score(NDS) via a series of behavior tests every 24 h and survival time was recorded. The heart rate variability (HRV) indicators were extracted by the collected ECG signals, including RR interval (RRI), low frequency (LF), high frequency (HF) and LF/HF ratio. The power spectrum of δ, θ, α and β waves were calculated from EEG signal. The heart-brain network was constructed based on the indicators mentioned, and the transfer entropy algorithm was used to quantify the coupling strength applied to the prognosis for survival which was analyzed and compared by the area under curve (AUC) among nodes of different networks. Results There was a bidirectional interaction between the brain and the heart, and the strength of two-way coupling increased after ischemia. There was obviously increased coupling between HRV LF and EEG δ wave. Transfer entropy (AUC=0.717, P=0.010) was superior to the HRV (AUC=0.571, P=0.404) and EEG power spectrum (AUC=0.583, P=0.329) in prognostication. Conclusion The low-frequency coupling between heart and brain enhanced after cerebral ischemia, and the coupling index of heart and brain can improve the prognostic performance.

Keywords

• coupling between heart and brain
• transfer entropy
• prognosis