Intermittently “Pre-Excited” ECG after Accessory Pathway Ablation: Unsuccessful Procedure or a Complication?

Figure 1

(a) Surface ECGs of the patient. (a) The ECG before the first ablation. A short PR interval, a delta wave. and a widened QRS are clearly seen. Panels (b) and (c) show ECG pattern after the first ablation. (b) Twelve ECG leads show three beats: the first and the third are with the short PR and the wide QRS, while the second beat is normal. (c) The continuous recording of the lead I shows alternation of the PR interval and the QRS.