| S1
The S wave is the first downward deflection after the R wave. A prominent S wave in Lead I will qualify.
Q3
The Q wave is defined as the first downward deflection after the P wave. The Q wave may or may not be present on a normal ECG.
T3
As mentioned, the T wave represents ventricular depolarization and can be identified after the QRS complex. A T wave may deflect upward and last approximately 0.04 - 0.08 seconds. The finding of an inverted T wave will come in Lead III.
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