PMC6342333_01
Chronological reports from the implantable cardiac monitor. A: Episodes of paroxysmal atrial fibrillation leading into the index procedure (white arrow), absence of detected tachyarrhythmias over the following 8 months, and subsequent recurrence of atrial arrhythmias (black arrow). B: Recurrence in the atrial arrhythmia burden and no further events following reisolation of the superior vena cava (white arrow). AT/AF = atrial tachycardia/atrial fibrillation; V. rate = ventricular rate.
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Interrogation of this device showed episodes of AF (Figure 1A) and pauses of 4 seconds following AF termination, corresponding to episodes of presyncope. However, the patient subsequently re-presented with recurrent paroxysmal AF (Figure 1A), and a repeat procedure was undertaken.
Intracardiac electrograms with the Achieve catheter (labeled PV [pulmonary vein] and SVC [superior vena cava] in the respective panels) and coronary sinus catheter (labeled CS). A: The Achieve catheter in the right superior pulmonary vein (RSPV), demonstrating spontaneous activity (box) while atrial fibrillation is seen on the CS catheter, reflecting electrical isolation. Low-amplitude activity is observable in the background, most prominently the distal electrodes of the RSPV, reflecting far-field signals from the SVC and appearing to organize at the end. Artefact from phrenic nerve pacing has been marked (white arrow). B: The Achieve catheter in the RSPV, as the tachycardia became organized, demonstrating apparent 2:1 conduction into the atria, following isolation of the vein. C: The Achieve catheter in the SVC postisolation, demonstrating independent rapid activity in the SVC, not perturbing rhythm in the atria or initiating atrial arrhythmias.
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Far-field signals with conduction into the atrium were observed with the Achieve catheter in the right superior pulmonary vein (RSPV), even following confirmation of RSPV isolation (Figure 2A). Following these applications, SVC-RA entry and exit block was confirmed with pacing, and further, spontaneous independent electrical activity was noted within the SVC, not perturbing sinus rhythm (Figure 2B and C).
Fluoroscopic views demonstrating superior vena cava (SVC) occlusion and catheter positions: A: Right anterior oblique. B: Left anterior oblique. C, D: Corresponding views of CARTO 3 activation maps of the right atrium, with annotation of the sites of earliest activation (white), ablation (red), and phrenic capture (yellow): C: right anterior oblique; D: left anterior oblique.
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Three applications of cryoenergy were made at the SVC-right atrial (RA) junction (Figure 3A and B). The SVC had reconnected, with voltage and activation mapping tracing the site of reconnection to the anteromedial aspect of the SVC-RA junction (Figure 3C and D).