Which ECG wave is characterized as a downward wave following the P wave?

The wave characterized as a downward wave following the P wave is the Q wave. In an electrocardiogram (ECG), the P wave represents atrial depolarization, and the subsequent Q wave is part of the QRS complex, which represents ventricular depolarization. The Q wave is specifically the first negative deflection after the P wave, while the R wave is the first positive deflection and the S wave is the subsequent negative deflection. Understanding the sequence and characteristics of these waves is essential in analyzing heart activity and identifying potential cardiac conditions.