人体心脏舒张最大吸力的模拟实验研究

目的:模拟研究人体心脏舒张早期潜存的心室最大负压.材料与方法:先在血液循环体外模拟装置上模拟正常生理情况下的左、右心室心动周期压力曲线,然后近似阻断房室瓣,分别测定左、右心室压力.结果:模拟实验得到的左、右心室心动周期压力曲线和正常生理情况下的左、右心室心动周期压力曲线非常接近.近似阻断房室瓣时,左、右心室舒张的负压平均值分别是-93.25 mmHg(-12.43 kPa)和-10.28 mmHg(-1.37 kPa).结论:(1)模拟得到的实验结果可以定性地说人体心脏舒张和静脉血液回流心生物动力学关系;(2)心脏舒张时心室压力的减低(负压)是形成静脉-心房-心室压力梯度的根本原因,心脏舒张所产生的舒张吸力是静脉血液回流心室的主要动力,即静脉血液回流心脏是心脏舒张吸力作用的结果;(3)心脏前负荷产生的机理应该是心脏舒张抽吸静脉血液回流心脏所需的吸力;(4)静脉血液在被抽吸回流心室腔的过程中对心室肌没有伸展作用,即Starling心定律没有心脏舒张动力学基础.

The largest diastolic suction of human heart in an analogue experiment

Objective: To study the ventricular largest negative pressure potentially existing in the forepart of the relaxation of a human heart in simulated experiment of an extracorporeal circulation. Materials and methods: Firstly, the left and right intraventricular pressure were measured by using extracorporeal circulation simulator to imitate the cyclic pressure changes that mimic the normal human heart. Then, the related pressure was measured again with the atrioventricular (a-v) valves approximatingly occluded during the diastole. Results: The left and right ventricular pressure curves of each cardiac cycle from the analogue experiment are much close to the pressure curve in human physiological system. While approximatingly occluding the a-v valves, the maximum negative pressure of the left and right ventricles were -93.25 mmHg (-12.43 kPa) and -10.28 mmHg (-1.37 kPa) on average separately. Conclusion: The experimental results from the circulatory simulator can qualitatively illustrate the biodynamic relationship between human heart's diastole and venous blood return to the heart. During diastole, the reduction of intraventricular pressure (negative pressure) is the basic reason for the pressure gradient of vein-atrium-ventricle passageway. The diastolic suction created by the heart working in the diastole is a main motive power for venous blood return to ventricles. In other words, venous return is the result of the action of diastolic suction. So, the mechanism of the heart preload should be diastolic suction force demanded to draw the venous blood back to the heart-venous blood itself has no extending influence on ventricular muscle fibers in the process of being sucked back into ventricles. That is to say Starling's Law of the Heart has no diastolic dynamic basis.