Two pacing spikes on the T wave in a single-chamber pacemaker: What is the mechanism?

Abstract

We report a case of a 54-year-old female, known symptomatic sick sinus syndrome, who had undergone a single-chamber pacemaker (VVI, St. Jude Medical, VERITY ADxXL SC SN 2413520) implantation in 2011. Electrocardiography (ECG) performed on a recent visit to the pacemaker clinic showed intermittent double pacing spikes on top of the T wave (Fig. 1A). What is the mechanism?

Keywords

• Single-chamber pacemaker
• Double pacing spike
• AutoCapture phenomenon
• R-on-T phenomenon