Pulmonary veins as a source of nonsinus heart rhythm

A 37-year-old man with a history of paroxysmal atrial fibrillation (AF) was admitted to the Cardiology Department to undergo a catheter ablation (CA) with pulmonary vein (PV) isolation.He complained of frequent, very symptomatic, short-lasting heart palpitations.On admission, the patient was stable and his vital signs were normal.All electrocardiograms and Holter recordings suggested focal origin of the arrhythmia.During electrophysiological study two coexisting rhythms were recorded.The first rhythm (Figure 1A) was characterized by positive p waves in leads I, II, aVL, biphasic in V1 and negative in aVR -and was determined to be sinus rhythm (SR).The second rhythm (Figure 1B) had slightly different P wave morphology; P waves were isoelectric in lead I and significantly wider and bifid in II, III, aVF and V1, which suggested its origin to be localized in the left atrium.After transseptal puncture 3D geometry of left atrium and PVs was created using the OCTARAY and CARTO 3 System (both Biosense Webster, Irvine, CA, US).The earliest atrial activation -62 ms before surface P wave -was recorded during the second rhythm inside the common ostium of the left PVs (Figure 1C).This further confirmed the left PVs as the source of the arrhythmia.Therefore PV isolation procedure was started and after left common ostium ablation spontaneous return of SR was observed (Figure 1D-E).After the completion of the entire ablation procedure also including the isolation of right PVs no further arrhythmias were recorded during hospitalization and the patient was discharged in a symptom-free state the following day.Pulmonary veins' role as a source of ectopic beats precipitating AF is well-established and as such their isolation via CA is a standard method of treatment in patients with AF [1].However, stable rhythms arising from PVs rank among the rarities with only a few reports of such rhythms [2][3][4].A few diagnostic algorithms have been proposed to differentiate the source of atrial extrasystoles.Kistler et al. [5] proposed a P wave algorithm beginning with the assessment of the morphology of the P wave in lead V1.If it is predominantly positive and bifid, also in lead II, while the inferior leads are non-negative, then the arrhythmia most probably originates in the left PVs.However, the final diagnosis can only be determined during electrophysiological study.This case demonstrates how an ectopic rhythm can mimic normal SR with the subtle differences in P wave morphology being visible only on careful examination.These particular AF cases were formerly named "focal" or "lone" AF and respond very well to PV isolation.