Potassium leaves the cell resulting in the cell becoming increasingly negative; at 60-70 mVmilliVolt; the ECG is usually calibrated to display 1mV = 10mm of amplitude. 1. Six Second ECG Guidebook (2012), T Barill, p. 200, the cell’s fast sodium channels begin to be receptive to causing another 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... – a period known as relative refractory periodIn phase 3 of the action potential, once the cell repolarizes to threshold potential to –90 mV, the cell’s ion channels are once again receptive to depolarization; this period is also called the supernormal period - minimal impulse energy is... or the supranormal period.
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. 202