The PR segmentA line between waves. Segments measure time between waves (waves are not included in a segment). While waves are fairly self-explanatory, intervals measure time from the start of one wave to the start of another wave (an interval includes at... is the line between the end of the P waveA wave generated from the depolarization of the atria; the P wave is upright when originating from the SA node. The P wave represents the depolarization of the right and left atria. The P wave begins with the first deviation... and the beginning of 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.... The PR segment signifies the time taken to conduct through the slow AV junctionConducts the impulse through the fibrous plate that separates the atria and the ventricles; consists of the AV node and the bundle of His; functions also to slow the conduction speed to allow for atrial conduction prior to ventricular conduction.... This delay allows for atrial kickThe contraction of the atria prior to ventricular contraction causes an increased volume and stretch to the ventricles – resulting in increased force of contraction and increased stroke volume (Starling’s Law); this extra stroke volume increases cardiac output by 10-35%..... The PR segment also serves as a benchmark for the isoelectric lineAlso called the baseline, the straight line that is present when no electrical activity is present. The baseline or isoelectric line is a reference point for the waves, intervals and segments.While the PR segment is often used as the baseline,....
In Figure 4.12, several ECG componentsAn ECG is composed of a series of waves and lines usually ordered into some repeatable pattern. The waves and lines are displayed on either a two dimensional screen or on ECG paper. The height of the tracing represents millivolts... are labelled. Note that a waveformA wave of an ECG. 1. Six Second ECG Guidebook (2012), T Barill, p. 209 is produced when the electrical potential of cardiac cell membranes change. During atrial 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..., the atrial cell membranes quickly become more positive producing a P wave. The baselineThe baseline or isoelectric line is a reference point for the waves, intervals and segments. While the PR segment is often used as the baseline, the TP segment - between the end of the T wave and the beginning of... or isoelectric line represents nothing more than an absence of voltage change to the cardiac cells.
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. 81