心脏搏血的生物力学和心电变化

Biomechanics of cardiac blood pumping and electrical changes of the heart

心电学和心脏力学虽然经历了巨大进展,但有关基本理论却长期止步不前,心电变化的相关研究仍存在诸多难点。鉴于实验医学对微观量化方法存在过分依赖,同时心电变化和心脏机械运动长期被视为两个独立的过程,本文首先从宏观角度探讨心脏收缩舒张时存在于整个弹性负荷系统中各种作用力的动态特征,然后通过在启动"兴奋-收缩偶联"之后心脏机械运动和心电变化始终存在前后定位关系这一事实,指出两个并存的过程实际上是一个完整事物的不同侧面。最后,对调控膜离子通道所涉及的各种电及力学因素综合加以考虑,整个心电变化过程即可被区分为3个不同性质的阶段;前驱性的兴奋形成及传导,收缩过程伴发的肌源性心电变化及最后由心脏快速弹性舒张促成的全面恢复。

Despite the significant progress in the fields of electrocardiology and cardiac biomechanics,theoretic limitations still exist and many problems on mechanism underlying the electrical changes of the heart still remain to be solved.Based on the fact that experimental studies deeply rely on the microscopic and quantitative information,and the electrical changes and mechanical activities of the heart have long been treated as two individual processes,dynamic forces generated in the whole spring-loading system during the cardiac contraction and relaxation were discussed first from a macroscopic view.Next,the temporal co-relationship between the electrical and mechanical processes after ＂excitation-contraction coupling＂ was particularly identified,which indicated that the intertwined electrical and mechanical activities,in their nature,are integrated parts of a same process.Finally,once all the electrical and mechanical ＂gating＂ mechanisms were taken into consideration,the electrical changes of the heart could be classified into three different phases： the preceding excitation formation and conduction,the myogenic changes during ventricular contraction,and the complete restoration of the heart both mechanically and electrically during active relaxation.