Pulmonary Vein Exit-Block During Radio-Frequency Ablation of Paroxysmal Atrial Fibrillation
A 34-year-old man with a history of labile hypertension was referred for focal ablation of paroxysmal atrial fibrillation (AF). The patient reported multiple episodes of palpitations since his late teens. Documentation of palpitations in the months preceding ablation had revealed AF. At electrophysiological study, there was no inducible supraventricular tachycardia, although dual AV nodal physiology was present. There was no evidence of an accessory pathway. During the study, AF developed. Cardioversion was attempted numerous times, with early recurrence of AF each time. Mapping of the initiating atrial beats postcardioversion revealed a focus in the right superior pulmonary vein (RSPV). Radio-frequency current was delivered to the ostium of the RSPV during AF. Exit-block developed between the pulmonary vein and the rest of the atria during energy delivery. Sinus rhythm was restored simultaneously. Figure 1 demonstrates the conversion from AF to sinus rhythm, while “fibrillatory activation” continues in the RSPV. Figure 2 shows spontaneous termination of pulmonary vein fibrillation 20 minutes after ablation. Although exit-block from the pulmonary veins is well-described, we believe this case to be unique because of the immediate restoration of sinus rhythm on achievement of exit-block. It demonstrates that pulmonary vein foci play a role not only in the initiation of atrial fibrillation, but also in its maintenance. Multiple attempts of programmed atrial stimulation after ablation did not reinitiate AF in this patient.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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