What does the Q wave represent on an EKG?

The Q wave on an electrocardiogram (EKG or ECG) represents the first negative deflection seen after the P wave. It is part of the QRS complex, which reflects ventricular depolarization. The Q wave is typically the initial downward deflection before the R wave (which is the first upward deflection) and indicates the electrical activity occurring in the ventricles as they prepare to contract.

Understanding the significance of the Q wave is important in interpreting EKGs, especially in recognizing various cardiac conditions, such as myocardial infarction, where the presence of abnormal Q waves (Q wave infarction) may suggest previous heart muscle damage.

The other options describe different components or phases of the cardiac cycle but do not pertain to the definition of the Q wave. The first positive deflection after the P wave corresponds to the R wave, not the Q wave. The period of electrical inactivity refers to repolarization phases occurring after the action potential, and the T wave recovery phase is specifically related to ventricular repolarization, distinctly different from the Q wave's role in depolarization.