Case report: an unstable wide QRS complexes tachycardia after ablation of a poster-septal accessory pathway: What is the mechanism?

INTRODUCTION: Differentiation of wide QRS complex tachycardia required repeated electrophysiological stimuli and mapping. However, instability of tachycardia would increase the difficulty in differential diagnosis. SYMPTOMS AND CLINICAL FINDINGS: In this paper, we reported a wide QRS tachycardia following ablation of an atrioventricular reentrant tachycardia participated by a poster-septal accessory pathway. Limited differentiation strategy was performed because the wide QRS tachycardia was self-limited and with unstable hemodynamics. We analyzed the mechanism of the wide QRS tachycardia by only 4 beats ventricular overpacing. On the basis of the last ventricular pacing, an atypical atrioventricular nodal reentrant tachycardia was confirmed. INTERVENTION AND OUTCOMES: After slow-pathway modification, the wide QRS tachycardia was eliminated. CONCLUSION: It was an atypical atrial-ventricular node reentrant tachycardia with right bundle branch block. Reasonable analysis based on electrophysiological electrophysiologic knowledge was the basis of successful diagnosis and treatment.