Incessant wide QRS tachycardia after pulmonary vein isolation and pacemaker implantation in a patient with tachycardia-bradycardia syndrome.

摘要

A 51-year-old patient underwent pulmonary vein isolation due to drug refractory symptomatic paroxysmal atrial fibrillation. (AF). Sino-atrial nodal dysfunction with a corrected sinus node recovery time of 994 msec was discovered, which led to the implantation of a dual-chamber rate-responsive pacemaker (Identity ADx XL DR model 5386, St Jude Medical, Sylmar, CA, USA). Five months postimplant, he presented with palpitations and exertional dyspnea. A 12-lead ECG revealed a wide QRS tachycardia, with a rapid regular ventricular paced rhythm (120 beats per minute) and irregular P waves (Fig. 1). The real-time intracardiac electrograms revealed atrial and ventricular pacing, with occasional atrial sensing (Fig. 2A). A chest X-ray examination revealed that the atrial lead had dislodged and moved to the lower lateral wall of the right atrium. What is the mechanism of the incessant wide QRS tachycardia after pacemaker implantation?