呼吸调节对心肌缺血大白鼠的心率和血压变化影响的实验研究

Influence of respiratory regulation on the changes of heart rate and blood pressure in rats with myocardial ischemia

目的探讨呼吸频率的改变对心血管自主神经平衡的调节作用及其对心肌缺血后心律失常的影响。方法选取17只标准实验大白鼠,其中正常组9只,心肌缺血模型组8只,在麻醉下施行呼吸机机械通气改变大白鼠的呼吸频率,基础潮气量恒定10 mL/kg,改变呼吸频率(在基础呼吸频率上升高10%、20%和降低10%、20%)。连续记录心率和血压,分析呼吸频率变化与心率变异(heart rate variability,HRV)、血压即时变异(blood pressure instant variability,BPIV)变化的关系;观察呼吸频率与心率变化、血压变化趋势的同步性;观察降低呼吸频率对两组心电的影响。结果 RR间期、血压与呼吸频率呈同步周期性变化;HRV及BPIV的中心频率均与呼吸功率谱密度中心频率一致,呼吸频率、心率和血压的变化趋势基本一致,尤其是心率和血压的变化趋势完全一致。结论呼吸调节下的HRV、BPIV符合呼吸性窦性心律不齐的生理机制,是RR间期变化的二次效应,反映了自主神经平衡调节的结果。心率和血压的同步性趋势变化与心搏频率有关。降低呼吸频率可能能减少心肌缺血引起的心律失常。

Objective To explore the role of respiratory rate change in regulating the balance of cardiovascular autonomic nerve and its influence on arrhythmia after myocardial ischemia. Methods Seventeen standard laboratory rats including 9 in normal group and 8 in myocardial ischemia model group were conducted with mechanical ventilation by ventilator to change respiratory rates. The fundamental tidal volume was constantly set at 10 mL/kg while respiratory rate changed（increasing by 10% and 20%, and decreasing by 10% and 20% of fundamental respiratory rate）. Blood pressure and heart rate were recorded continuously; the influence of respiration rate regulation on heart rate variability（HRV） and blood pressure instant variability（BPIV） was analyzed; the synchronism of respiration rate with changes of heart rate and blood pressure was observed; the effect of reduced respiration rate on HRV in the two groups was evaluated. Results The cyclical changes of RR interval and blood pressure coincided with respiratory rate. The central frequencies of HRV and BPIV were both consistent with that of respiratory power spectral density. The variation trend of respiratory rate was essentially in agreement with that of heart rate and blood pressure, and especially, the variation trend of heart rate and blood pressure was completely identical. Conclusion HRV and BPIV under respiratory regulation correspond with physiological mechanism of respiratory sinus irregularity. It is the secondary effect of RR interval changes and reflects the results of autonomic nervous balance. The frequency of heart beat contributes to the synchronous changes of heart rate and blood pressure. It may reduce the incidence of myocardialischemiainduced arrhythmia to slow respiratory rate.