While often a quick look is sufficient to determine whether the QRS complexThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also... is upright or inverted, occasionally a QRS complexA collection of waveforms (i.e. QRS complex and the ECG complex). 1. Six Second ECG Guidebook (2012), T Barill, p. 194 requires a simple calculation to arrive at a net deflection.
Figure 6.10 outlines the steps required to arrive at a net deflection. The orientation (up or down) of the QRS complex ‘D’ is not easily established. The net deflection would equal the sum of the separate three deflections: 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... of -3 mm, an R waveFollowing the depolarization of the interventricular septum, ventricular depolarization then progresses from the endocardium through to the epicardium across both ventricles producing an R wave and an S wave. An R wave is the first positive deflection of the QRS... of +4 mm and an S waveAn S wave is the first wave after the R wave that dips below the baseline (isoelectric line). The end of the S wave occurs where the S wave begins to flatten out. This is called the J point. Figure... of -7 mm = net deflection of -6 mm. Calculating net QRS deflection is a well-utilized exercise in identifying the QRS axis.
Figure 6.10 outlines the steps needed to determine whether a QRS complex is upright, inverted or neutral. For QRS complexes such as ‘A’ and ‘E’, the answer is straightforward. For the other QRS complexes (B-D, F), the net deflection of the QRS complex must be calculated. Take QRS complex ‘B’. The R wave is 5 mm in height and the S wave is 7 mm in depth leaving a net deflection of +5-7 or -2. The QRS complex ‘B’ has a negative net deflection of -2.
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. 162