A 70-year-old man with a long history of coronary artery disease is in the Emergency Department complaining of dyspnea:

• Electronic pacemaker
• Normal sinus rhythm, 60/min
• DDD pacing (atrial sensed, ventricular paced rhythm)

The atrial activation (P) is sensed and is followed by a ventricular paced output (the “spike”, a sharp vertical deflection) and ventricular activation (QRS).