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Figure 5 Torsade de Pointes Before and After Pacemaker Implantation in a Patient With Paroxysmal Atrial Fibrillation and High-Degree Atrioventricular Block in the Absence of Drugs
(A) Narrow QRS escape rhythm at an average rate of 36 beats/min. After a long cycle (1.88 s), a ventricular couplet, probably representing triggered activity, begins a series of short-long sequences that culminate in torsade de pointes. At the time of pacemaker implantation, sinus rhythm with 1:1 atrioventricular conduction was evident and a dual-chamber was implanted. The device was left at nominal settings (including a lower rate limit of 60 beats/min). (B) Several hours after pacemaker implantation the patient had recurrent torsade de pointes. The trace shows sinus rhythm (75 beats/min) with appropriate tracking and ventricular pacing. A premature complex (*) starts a post-extrasystolic pause that terminates with a sinus complex with atrial pseudo-fusion (the atrial pacing stimulus falls on the P-wave [arrow]). Ventricular bigeminy follows and culminates in torsade de pointes despite a normally functioning pacemaker. The lower rate was increased to 120 beats/min and gradually decreased during the next week to 80 beats/min. No further arrhythmias occurred.
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