Normal ventricular depolarizationThe depolarization of the myocardium is represented on an ECG by a series of waveforms, one for atrial depolarization and soon after a larger waveform for ventricular depolarization. Normal ventricular depolarization begins with the septal fascicle of the left bundle... begins with the septal fascicleWith regards to the heart, a fascicle is a smaller branch of the left bundle branch – two fascicles serve the left ventricle (one of which divides again); the three fascicles ensures rapid depolarization across the entire left ventricle. 1.... of the left bundle branch (causing a Q waveA Q wave is the first negative deflection of the QRS complex that is not preceded by a R wave. A normal Q wave is narrow and small in amplitude. Note that a wide and/or deep Q wave may signify...) followed by a simultaneous depolarizationThe rapid influx of positive ions (sodium and/or calcium) into a cell – depolarization is necessary for contraction to occur. A depolarizing wave moves through the myocardium on average along a trajectory or vector. A vector is a force moving... of the remaining ventricular walls via the right and left bundle branchesThe bundle of His terminates in the right and left bundle branches, insulated rapidly conducting electrical pathways that connect with the Purkinje network and thus begin depolarizing waves across the ventricles; the left bundle branch splits into three smaller branches.... The left bundle branch splits into the septal, anterior and posterior fascicles. A damaged conduction system can lead to the blockage of any or all of these bundle branches (or fascicles).
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 151