Transient cardiac electrophysiological changes in a rat model of subarachnoid haemorrhage: a brain-heart interaction.

AIMS: Subarachnoid haemorrhage (SAH) is one of the causes of sudden cardiac death (SCD). However, the time course of ventricular arrhythmias and potential mechanisms responsible for this effect after SAH remain unknown. OBJECTIVE: This study aims to investigate the effect of SAH on ventricular electrophysiological changes and its potential mechanisms in long-term phase. METHODS AND RESULTS: We examined the ventricular electrophysiological remodelling and potential mechanisms in a Sprague Dawley rat model of SAH at six time points (baseline, and Days 1, 3, 7, 14 and 28) and explored the potential mechanisms. We measured the ventricular effective refractory period (ERP), ventricular fibrillation threshold (VFT) and left stellate ganglion (LSG) activity at different time points before and after SAH. We also detected neuropeptide Y (NPY) levels in plasma and myocardial tissues by enzyme-linked immunosorbent assay, and quantified NPY 1 receptor (NPY1R) protein and mRNA expression levels by western blotting and quantitative real-time reverse transcription-polymerase chain reaction, respectively. Subarachnoid haemorrhage gradually prolonged QTc intervals, shortened ventricular ERP and reduced VFT during the acute phase, peaking at Day 3. However, no significant changes were observed from Days 14 to 28 compared to Day 0. Subarachnoid haemorrhage gradually increased LSG activity, increased NPY concentrations and up-regulated NPY1R expression in the acute phase of SAH, peaking at Day 3. However, no significant variations were found from Days 14 to 28 compared to Day 0. CONCLUSION: Subarachnoid haemorrhage increases the transient susceptibility of VAs in the acute phase, and the underlying mechanisms for this response included increased sympathetic activity and up-regulated NPY1R expression.