Page 9 - EKG STUDY GUIDE

Figure 4: EKG Grid

Waves, segments and intervals

 Waveform: refers to movement away from the isoelectric line either upward (positive)
deflection or downward (negative) deflection.
 Segment: line between two waveforms.
 Interval: waveform plus a segment.
 Complex: several waveforms

The Normal Electrocardiogram Complexes

Atrial Activation:
P wave: the deflection produced by atrial depolarization. The normal P wave in standard, limb,
and precordial leads does not exceed 0.11s in duration or 2.5mm in height.

Ventricular Activation:
QRS complex: represents ventricular depolarization (activation). The ventricle is
depolarized from the endocardium to the myocardium, to the epicardium.
Q (q) wave: the initial negative deflection produced by ventricular depolarization.
R (r) wave: the first positive deflection produced by ventricular depolarization.
S (s) wave: the first negative deflection produced by the ventricular depolarization that
follows the first positive deflection, (R) wave.

National Healthcareer Association EKG Study Guide (Ea) 11