In a QRS complex, if the first wave is upward, what type of wave is it?

In a QRS complex, the first wave is referred to as the R wave when it presents as an upward deflection. The QRS complex represents ventricular depolarization and is constituted by three main components: the Q wave, the R wave, and the S wave.

The R wave is specifically characterized as the first positive deflection seen after the Q wave. If the initial wave in the QRS complex is upward, it confirms that it is indeed the R wave. This upward movement indicates that the electrical activity is progressing through the ventricles in a way that generates a positive deflection on the EKG.

Knowing this classification helps in understanding various conditions represented on an EKG, as the characteristics of these waves (including whether they are positive or negative) can provide crucial diagnostic information. The other waves mentioned—U wave, P wave, and S wave—do not refer to this initial upward deflection in the QRS complex, thus clarifying that the R wave is the correct identification here.