Electrophysiologic Characteristics And Radiofrequency Catheter Ablation Of Atrial Arrhythmia Originating From Superior Vena Cava

Objectives:To analyze the characteristics of surface electrocardiogram (ECG) and electrophysiologic features and to investigate the strategy of radiofrequency catheter ablation (RFCA) of atrial arrhythmia originating from superior vena cava (SVC).Methods:The study population consisted of14patients (6males, aged56±7years) from2003-2013underwent electrophysiologic examination and radiofrequency catheter ablation of atrial arrhythmia originating from SVC, including premature atrial contraction (PAC), atrial fibrillation (AF), atrial tachycardia (AT). The14patients had the history of palpitation for8±7years. The ECGP’wave morphlogy of PAC or AT and the electrophysiologic characteristics were analyzed. During PAC which inducing AF or AT, the origin sites with earliest atrial activation were mapped under the guidance of traditional mapping technique or cardiac three-dimensional (3D) mapping system, combined with SVC angiography. After the SVC origin of triggering arrhythmia was determined, RFCA of the SVC origin was performed by focal, segmental or circular ablation.Results:In the14patients with atrial arrhythmia originated from SVC, the P’wave morphology in lead I was positive in13patients and isoelectric in1patient; the P’ waves in lead Ⅱ were positive in14patients; the P’waves in lead III were positive in12patients and positive/negative in2patients; the P’waves in lead aVF were positive in13patients and isoelectric in1patient; the amplitude of the P’waves during atrial arrhythmia were significantly higher than the one of P waves during sinus rhythm in the inferior leads. Similar to the P waves during sinus rhythm, the P’waves in lead aVR were negative in all the14patients; the P’waves in lead Ⅵ were positive in5, negative in3, positive/negative in4and isoelectric in2patients, respectively. The SVC potentials could be recorded in SVC and the right superior pulmonary vein (RSPV) in8patients, which was ahead of the time of coronary sinus ostium (CSo) by50±11ms during sinus rhythm, and by93±20ms during atrial premature (P<0.01). The abnormal electric activities from SVC may trigger atrial fibrillation and atrial tachycardia. The potentials in SVC remained quick and chaos electric activity after isolation of SVC and AF transferring to sinus rhythm from a few minutes to half an hour in1patient. Automatic electric activity from SVC occurred in2patients after isolation of SVC. RFCA eliminated AT in5patients by focal ablation. RFCA eliminated the PAC and AT triggering AF by segmental or circular ablation in9patients under the guidance of Carto3D mapping system. During ablation,1patient occurred transient sinus arrest, and1patient had cardiac tamponade which was most likely related to ablation of pulmonary veins. No other complications during peri-operative period and the period of follow up.Conclusions:Atrial arrhythmia originating from SVC has some typical surface ECG characteristics. The amplitude of P’waves in inferior leads Ⅱ, Ⅲ and aVF was significantly higher than the P waves during sinus rhythm. The time difference of SVC potential ahead of CSo between atrial premature/AT and sinus rhythm has some help to differentiate the triggers originating from SVC and may improve the success rate. Because SVC is anatomically adjacent to the sinus node and the right phrenic nerve,3D mapping system and SVC venography may be helpful to identify the focal anatomy and decrease the complication rate.