Which complex on an EKG signifies ventricular depolarization?

The QRS wave represents ventricular depolarization on an EKG. This phase of the cardiac cycle is crucial because it indicates the electrical activity that precedes the contraction of the ventricles, leading to the pumping of blood throughout the body.

The QRS complex is characterized by its sharp, spiked appearance and encompasses three main deflections: the Q wave (the initial downward deflection), the R wave (the subsequent upward deflection), and the S wave (the downward deflection following the R wave). The duration and shape of the QRS complex provide important information about the functionality and conduction of electrical impulses through the ventricles.

In contrast, the P wave signifies atrial depolarization, which occurs before the QRS complex. The T wave represents ventricular repolarization, the phase when the ventricles reset electrically after contraction. The QT interval encompasses the time from the start of the QRS complex to the end of the T wave, indicating the total time taken for both depolarization and repolarization of the ventricles, but it does not specifically indicate depolarization alone. Therefore, the QRS wave is the definitive marker for ventricular depolarization in the EKG reading.