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. 2015 Jun 6;1(5):379–381. doi: 10.1016/j.hrcr.2015.05.002

Figure 1.

Figure 1

A: Simultaneous recordings of surface ECG leads II, III, and V1 and intracardiac coronary sinus (CS) and persistent left superior vena cava (PLSVC) electrograms during atrial fibrillation (AF) initiation. The circular mapping catheter is positioned within the PLSVC. During the first 2 sinus beats, left atrial far-field signals (arrow) are recorded first, followed by PLSVC signals (asterisk). During AF initiation, a reversal of the activation sequence is observed, with PLSVC potentials recorded very early (star) compared to the P wave on the surface ECG and to the atrial signals recorded on the CS catheter. Of note, the atrial activation sequence is from distal to proximal on the CS during AF initiation, indicating a probable left atrial origin. The AF cycle length is shorter in the PLSVC than in the CS. B: The circular mapping catheter is still positioned within the PLSVC during the atrial tachycardia originating from the CS. Spontaneous PLSVC potentials (*) distinct from the atrial far-field signals (A) are observed on the circular mapping catheter.