Which ECG feature indicates ventricular activation as the impulse travels through the ventricles?

• A. Rhythm Strip
• B. Segment
• C. QRS Complex
• D. SA Node

Answer: (C)

The QRS complex shows ventricular activation. It’s the set of sharp deflections that follows the P wave and represents the rapid depolarization of the ventricles as the impulse travels through the ventricular myocardium. This activation triggers the ventricles to contract. The SA node’s activity is seen as the P wave, not the ventricular activation. A rhythm strip is the overall tracing, and a segment is a specific interval within the trace (like the PR or ST segment); neither specifically marks the moment the ventricles depolarize. So the QRS complex is the best indicator that the impulse is moving through and activating the ventricles.