| Part I:The Incidence and Characteristics of Vagal Response during Catheter Ablation of Atrial Fibrillation and the Effect on the Ablation ResultsBackgroundCardiac autonomic nerve system played an important role in occurring and maintaining of atrial fibrillation (AF). There are no data to evaluate the relationship between autonomic nerve function modification and recurrent AF after stepwise linear catheter ablation. The aim of this study was to evaluate the incidence, characteristics of vagal response in left atrium (LA) during the stepwise linear catheter ablation of AF and the effect on the results of ablation.MethodsThere were250consecutive AF patients (192men; mean age,54.2±10.3years; mean left atrial diameter,47.5±6.0mm,79with persistent AF) underwent stepwise linear catheter ablation of AF enrolled in this study. Vagal response, defined as transient ventricular asystole, atrioventricular block, or an increase in RR interval by50%, was recorded and the sites of Ganglionated plexi (GP) were marked around the root of pulmonary vein (PV) on the three dimensional geometry of LA. Abolition of all evoked vagal response in LA was completed during the procedure.ResultsAll the patients underwent successful catheter ablation of AF and130(52%) patients experienced vagal response during the ablation. The most common endocardial sites where vagal response was elicited were between LA and the root of left superior PV (LSGP) in119patients (91.5%), between left inferior and LA (LIGP) in61patients (46.9%), and between the right superior PV and LA (RAGP) in26patients (20%), between the right inferior PV and LA (RIGP) in6patients (4.6%). After a mean follow-up of18.4±5.9months,165(66%) patients were free from recurrence of atrial arrhythmia following the ablation. The Kaplan-Meier cure showed that the patients with vagal response were less likely to have recurrent AF than those without vagal response (P=0.004, log-rank test). In univariate analysis, persistent AF (HR=1.462;95%CI0.942-2.267, P<0.09), type2diabetes (HR=2.39;95%CI1.418-4.031, P=0.001), vagal response (HR=0.562;95%CI0.347-0.828, P=0.005), and left atrial diameter (HR=1.044;95%CI1.008-1.082, P=0.016) were significantly associated with the recurrence of AF after the procedure. Multivariate Cox regression analysis revealed that type2diabetes (HR=2.203;95%CI1.303-3.727, P=0.003) and vagal response (HR=0.575;95%CI0.371-0.889, P=0.013) were independent predictors of recurrent AF after ablation.ConclusionVagal response could be commonly observed during the stepwise linear catheter ablation of AF and the most common sites were between LA and the root of left superior PV. The adjunctive vagal denervation of LA during catheter ablation could significantly reduce recurrence of AF during the follow-up. Part II:Increased Resting Heart Rate following Stepwise Radiofrequency Catheter Ablation of Patients with Atrial Fibrillation and BradycardiaBackgroundThe increase of sinus-rhythm heart rate (HR) after pulmonary vein (P V) isolation in patients with paroxysmal/persistent atrial fibrillation (AF) has been observed in many studies, in which vagal denervation during the ablation procedure played an important role. The aim of this study was to evaluate the increase of resting HR following stepwise radiofrequency catheter ablation of patients with atrial fibrillation and bradycardia.MethodsThere were46consecutive patients (36men, mean age:55.8±12.3years, mean left atrial diameter:38.4±5.9mm,14with persistent AF).with sinus bradycardia underwent catheter ablation of AF enrolled in this study. Vagal response, defined as transient ventricular asystole, atrioventricular block, or an increase in RR interval by50%, was recorded in28patients (60.9%) during ablation. Vagal denervation was completed during the procedure.ResultsThe most common endocardial sites where vagal response was elicited were around the root of left superior PV (LSGP) in25patients (89.3%), around the inferior and posterior root of left inferior PV (LIGP) in12patients (42.9%), at the anterior root of right superior PV (RAGP) in6patients (21.4%), and at the posterior root of right inferior PV (RIGP) in1patients (3.6%). Following catheter ablation, the mean HR significantly increased from52.4±4.0at baseline to69.0±6.5bpm at three months (increased16.5±8.0bpm, P<0.001),67.3±6.0bpm at six months (increased14.9±7.4bpm, P<0.001),66.8±5.7bpm at twelve months (increased14.4±7.1bpm, P<0.001),66.1±5.9bpm at18months (increased13.7±7.3bpm, P<0.001), and67.6±5.5bpm at24months (increased15.0±7.7bpm, P<0.001) follow-up. The patients with an obvious vagal response during the procedure had a higher increase of resting HR at3months after ablation. During an average of27.1±6.8months follow-up,29patients had no recurrence of AF. No patients with the mean HR increased>25bpm resulting in symptoms necessitating therapy with rate-controlling drugs. ConclusionVagal denervation during stepwise linear catheter ablation for AF patients with bradycardia may result in increased HR, which was significantly correlated with the vagal response during the procedure. This change does not seem to resolve spontaneously after a follow-up of24months. Part Ⅲ:Endocardial Autonomic Denervation of the Left Atrium to Treat Vasovagal SyncopeBackgroundVasovagal syncope (VVS) is the commonest cause of recurrent syncope that can be debilitating despite optimal conventional therapy. The aim of this study was to evaluate the feasibility and efficacy of selective endocardial autonomic denervation in left atrium (LA) as an alternative treatment strategy in patients with highly systematic VVS.MethodsTen consecutive patients (mean age50.4±6.4years,7females) with a medium of3.5(2-20) recurrent episodes of VVS during the preceding year and positive head-up tilt testing (HUT) in whom standard therapies were ineffective or poorly tolerated were enrolled. Ganglionated plexi (GP) in the LA, identified by high-frequency stimulation, was targeted by radio frequency (RF) catheter ablation. The patients were then follow-up at3,6,12,24and36months including repeated HUT and Holter at3and12months.ResultsRF energy was applied at the left superior GP in10patients, right anterior GP in5, left inferior GP in3using an8mm ablation catheter. Vagal response, defined as transient ventricular asystole, atrioventricular block, or an increase in RR interval by50%, was observed during ablation in all GP sites. The end point of procedure was the inhibition of the vagal response at target sites. At30±16(13-55) months follow-up, no patient had any recurrence of syncope, all patients experienced significant improvement in symptom albeit5of10patients reported transient prodromes. No complication occurred.ConclusionComprehensive endocardial autonomic denervation of the LA is safe and effective in treating vasovagal syncope in medium term follow-up. |
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