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目的研究不同程度心肌收缩功能降低对心血管系统立位应激反应的影响 ,探讨心肌收缩功能改变在航天失重后心血管失调和立位耐力降低机理中的意义。方法以我们原有仿真血量减少后下体负压 (LBNP)暴露时心血管系统反应的模型为基础 ,对其心脏工作子模型中最大弹性系数 (maximumelas tance)乘以一个反映心肌收缩功能改变的系数。然后逐渐降低收缩功能改变系数 ,仿真血容量减少1 2 %后 ,心肌收缩功能降低 0 30 %后LBNP时心率 (HR)、血压 (BP)和心输出量 (CO)的变化。结果心肌收缩功能降低将使LBNP时 ,HR加快、BP降低和CO减小。结论心肌收缩功能降低导致心血管系统对立位应激的调节能力降低
Objective To study the effects of different degrees of myocardial contractile function reduction on cardiovascular system orthostatic stress and to explore the significance of the changes of myocardial contractile function in the mechanism of cardiovascular dysfunction and standing endurance reduction after aerospace weightlessness. Methods Based on our previous model of cardiopulmonary system response after LBNP exposure, we multiplied the maximum elasticity coefficient (maximumelas tance) in the heart working sub-model by a value that reflects changes in myocardial systolic function coefficient. Then, the changes of systolic function were gradually reduced. The changes of heart rate (HR), blood pressure (BP) and cardiac output (CO) in LBNP after simulating reduction of blood volume by 12% and myocardial systolic function decreased by 30% Results Myocardial contractile function will be reduced when LBNP, HR, BP decreased and CO decreased. Conclusions Decreased cardiac contractile function leads to a decrease in the ability of the cardiovascular system to regulate orthostatic stress