高心率对大鼠离体心脏心输出量的影响  

Depressed cardiac output at higher pacing rate in isolated working heart of rat

作　　者：余愿[1,2] 张琳[1] 余志斌[1] 

机构地区：[1]第四军医大学航空航天生理学教研室,陕西西安710032 [2]南昌大学医学院,江西南昌330088

出　　处：《中国应用生理学杂志》2013年第2期106-109,共4页Chinese Journal of Applied Physiology

基　　金：国家自然科学基金资助课题(31071044)

摘　　要：目的:为探明在负性力-频率关系范围内,增加心率对整体心脏泵血功能的影响及其可能机制。方法:采用离体大鼠工作心脏模式,左心室插入压力传感器,电刺激心脏搏动,观测心输出量、左心室内压力、主动脉压力的变化。结果:当心率从240 beats/min增加到300 beats/min时,心输出量显著性降低约20%(P<0.01),左心室收缩末压力(LVESP)下降仅4.8%(P<0.05),左心室舒张末压力(LVEDP)却升高139%(P<0.01),且左心房明显扩张;左心室压力从峰值降至75%的时间缩短,主动脉瓣关闭压力升高(P<0.01),射血时间明显缩短(P<0.01)。结论:高心率引起心输出量降低的机制与负性力-频率关系的形成机制可能并不相同。高心率致频率依赖性舒张增强作用使左心室压力加速下降,在主动脉压力曲线形态不变的条件下,导致主动脉瓣关闭压力升高,进而使得射血时间缩短,引起每搏量明显降低。当增加的心率不足以代偿每搏量的下降时,呈现心输出量降低。Objective： To observe the regulation of heart rate to cardiac pump function in the phase of negative force-freqnency relationship and their possible mechanisms. Methods： The left ventrieular pressure, aortic pressure, and cardiac output were measured in isolated working heart of rat from 240 to 300 beats/min of pacing rate. Results： Cardiac output of isolated working heart was decreased by a proximally 20 % （ P 〈 0.01） with the increase in the pacing rate from 240 to 300 beats/rain. Left ventricular end-systolic pressure （LVESP） was declined by 4.8% （ P 〈 0.05）, but left ventricular end-diastolic pressure （LVEDP） was elevated by 139% （ P 〈 0.01 ） with an increase in the pacing rate. Left atrium was enlarged at 300 beats/rain of pacing rate. The time from peak to 75% relaxation in left ventrieular pressure was shortened with the increased pacing rate. Pressure at aortic valve close was raised （ P 〈 0. 01） and ejection duration was shortened with the increased pacing rate （ P 〈 0.01）. Conclusion： Those above results suggest that there are different mechanisms between the depressed cardiac output at higher heart rate and negative foree-frequency relationship. The frequency-dependent acceleration of relaxation facilitates the decline of left ventricular pressure, and then may elevate the pressure of aortic valve close in the condition that the shape of aortic pressure curve stays the same. Therefore, the ejection duration is shortened at higher pacing rate. The shortened ejection duration may induce a decrease in stroke volume of the left ventricle. The increment of heart rate is not enough to compensate the decreased stroke volume. Finally, cardiac output shows a decrease at higher heart rate.

关 键 词：工作心脏 心输出量 主动脉瓣关闭压力 射血时间 

分 类 号：R337.2[医药卫生—人体生理学]