Dizziness in a patient with a permanent VVI pacemaker.

A 83-year-old woman with a single-chamber pacemaker implanted 15 years earlier was brought to the ED due to symptomatic bradycardia. ECG continuous monitoring allowed the diagnosis of atrial fibrillation with complete atrioventricular block in the setting of a complete failure to capture. The differing timing cycles of pacing outputs can confirm that sensing is preserved in the absence of a pacemaker programmer.