| Objective The purpose of this study is, through the intracardiac electrophysiological mapping and electrical isolation of the myocardial sleeves (MS) in the pulmonary veins (PVs) and superior vene cava (SVC) by radiofrequency catheter ablation (RFCA) in patients with paroxysmal atrial fibrillation (PAF), to demonstrate the feature of spontaneous electrical discharges in the MS before and after the isolation and their role in the initiation of atrial fibrillation, and investigate the characteristics of electrical connections between the MS and the atria. The long-term effects for the control of the PAF and complications of the isolation procedure by RFCA technique were also evaluated.Methods (1) Patient selection: The Electrophysiological study (EPS) and MS isolation were performed in patients with refractory and drug-resistant PAF and with no evidence of structural heart diseases. The atrial thrombus was excluded by the thrans-esophageal echocardiography (TEE) and/or multislice spiral computed tomography (MSCT). (2) Electrophysiological mapping: With circular mapping catheters in PV and SVC during the sinus rhythm, atrial pacing and during the episode of atrial tachyarrhythmias, both the MS and atria potentials were simultaneously recorded before and after the isolation. Their characteristics and the relationship between the MS and the atria were analyzed. (3)According to the activation sequence of MS potentials during sinus rhythm and atrial pacing, and to its change on radiofrequency current delivery, the number of the bundles and the type of electrophysiological connections between the MS and atria were evaluated.(4)Guided by circular mapping catheter, radiofrequency lesions were applied around the circumference of the arrhythmogenic veins or each PV or SVC at the ostia until the achievement of complete electrical disconnections between the MS and atria. During the follow-up, the effects were evaluated on the basis of the patient's symptom and Holter ECG monitoring. The complications of the vein stenosis were confirmed by the MSCT performed at the 3 months post isolation.Results: (1)Continuous 131 patients (mean age 53 + 10) with PAF underwent EPS and MS isolation by RFCA. (2)Spontaneous electrical discharges triggering or initiating atrial arrhythmias were recorded in 59 veins of 50 patients(38%), including 49 PVs and 10 SVCs. There were one or more patterns of discharges inside each arrhythmogenicvein, including frequent or bigeminal discharges in 38, short runs (in salvos) of discharges in 8 and continuous firing in 27. The total 23 onsets of PAF were documented, which were always preceded by short and fast atrial tachycardia or flutter-like activities driven by continuous electrical firing from veins with variable degrees of exit block. After the isolation with the end-point of complete loss of MS potentials during sinus rhythm and atrial pacing, 19 veins (32%) demonstrated spontaneous electrical activities, among which slow rhythm with an average rate of 38 +12 bpm was recorded in 12, occasional short runs of rapid rhythm in 4, and continuous rapid firing activities in 3. In 18 of 19 veins (95%) the spontaneous electrical activities showed complete dissociation with atria, and only one left superior pulmonary vein had intermittent conduction to the atrium which was blocked by another delivery of radiofrequency current. (3)A total of 116 veins were analyzed, including 100 PVs (PV group) and 16 SVCs (SVC group). In PV group, one bundle of electrophysiological connection was documented in 35 veins (35%), two bundle connections in 48(48%), multiple bundle connections in 11(11%), circumferential connections in 3 and no connection in 3. In SVC group, one bundle connection were found in 8 veins (50%), two bundle connections in 7 (43%), and multiple bundle connections in 1 (6.3%). (4) 159 procedures were performed in 131 patients, with two procedures in 25 cases and three procedures in 3. Among them, only an arrhythmogenic vein was isolated in 25 cases and empiric all PVs and/or SVC were isolated in the oth...
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