A 76-year-old woman presents with a persistently rapid heart rate that she attributes to her pacemaker. What does the ECG show?

A combination of the Q wave, R wave and S wave, the “QRS complex” represents ventricular depolarization. This term can be confusing, as not all ECG leads contain all three of these waves ...

Widening of the QRS complex. This usually requires a ... and it appears like a right bundle branch block in leads I and V6 with a broad, slurred S wave. Decreased amplitude of the P waves, an ...