Electromechanical Activation Sequence in Normal Heart

This article summarizes the recent experimental and theoretic data regarding the normal electromechanical activation sequence of the left ventricle (LV). First, the cardiac electrical sequence is presented with a brief insight into the wave front of electrical activation that develops from the organized transmural spread of action potentials. Second, the regional heterogeneity in electromechanical coupling and myofiber stretch-shortening kinematics are presented. Finally, the transmural shortening and lengthening sequences are linked with the myofiber architecture of the left ventricular wall to explain the global three-dimensional twisting deformation of the LV. Integrating the electrical and mechanical domains of myocardial function provides vital insights into the macroscopic physiologic behavior of a beating heart.