The QRS complex indicates ventricular depolarization. Depolarization triggers contraction of the ventricles.
Because of the larger tissue mass, the QRS complex is larger than the P wave. While the prototypical QRS complex consists of three wave components, one or two of these components may be missing.
In this step, measure the QRS interval from the end of the PR interval to the end of the S wave. Use calipers, marking paper or by counting small boxes. Normally this interval is 0.06 to 0.12 seconds (1.5 to 3 boxes).
- Does the QRS interval fall within the range of 0.08-0.12 seconds?
- Are the QRS complexes similar in appearance across the ECG tracing?