The Electrophysiological Properties Of Atrial Fibrillation And The Impact Of Radiofrequency Catheter Ablation

Background: the mechanism of atrial fibrillation(AF) has not been estimated clearly. In 1998, Haissaguerre of France found that the ectopic sources originated from pulmonary vein(PV) played an important part in the triggering of atrial fibrillation. And the circumferential pulmonary vein isolation(CPVI) has become the main treatment in most electrophysiological centers all over the world. However, the mechanism and the effect of CPVI are still questioned in some researches. At present, there are still researches focusing on the electrophysiological properties of atrial fibrillation, especially persistent atrial fibrillation(Pe AF). It is necessary to make further study concerning the electrophysiological characteristics of atrium, including PV, and its effects in AF.Objective: the purpose of this study was to observe and compare the electrophysiological feature before and after the treatment of catheter ablation among three groups, non-AF, paroxysmal atrial fibrillation(PAF) and Pe AF. Meanwhile, the possible trigger and maintain mechanism of atrial fibrillation was studied. Furthermore, its significance in evaluating the strategy of cathether ablation of atrial fribrillation was discussed.This study was divided into two parts.Part I: the electrophysiological characteristics of atrium in patients with AFMethods: 32 patients hospitalized for radiofrequency catheter ablation were included, 10 left accessory pathways(LAP) without AF in Control group, 12 in PAF group, 10 in Pe AF group. Some electrophysiological properties were measured and compared through electrophysiological study(EPS) after radiofrequency catheter ablation of LAP in control group, and intracardiac conversion through catheter ablation in PAF or Pe AF group: intra-right atrial conduction time(RACT), intra-left atrial conduction time(LACT), interatrial conduction time(ICT), and pulmonary vein antrum potential(PVAP) duration. ERPCSp, ERPCSd, CS-PVmax and Disp CS-PV,ERPPV, PV-CSmax, Disp PV-CS, Disp ERPLA were tested or calculated through coronary sinus(CS) and PV programmed electric stimulation. The repetitive atrial activity zone(RAAZ) and other special electrophysiological phenomena of during EPS were observed and compared.Results: 1. There were no significant differences in the intra-atrial and inter-atrial conduction time among three groups. 2.PVAP duration in AF was longer than control group, usually accompanied with complex fractionated potentials. 3. Decremental conduction between PVd and adjacent CS was detected among three groups, PV-CSmax is longer than CS-PVmax. 4.ERPpv was significantly reduced while Disp CS-PV, Disp PV-CS and Disp LAerp were increased in AF patients. 5. Most RAAZ of in AF group was significantly longer than in control group, and RAAZ by superior PV stimulation was longer than by CS stimulation. RAAZ in Pe AF group was longer than in PAF group. 6. Some special electrophysiological phenomena were observed in AF patient: extremely shortened ERPPV, gap conduction between PV and CS. 7. Despite the diversity between individuals, in general, most changes of properties were similar between Pe AF group and PAF group, but more obvious in Pe AF group. There were no significantly differences in Some properties change of inferior PV, especially right inferior PV(RIPV) in AF groups, including PVAP、CS-PVmax、ERP, and so on.Part II the characteristics of inducibility in AF and the impact of catheter ablationMethods: After the accomplishment of EPS, CSp、CSd、RSPV、LSPV were stimulated in turn, comparing the induction of AF in CS stimulation and PV stimulation among three groups. Then CPVI was proceeded in PAF group, while 2C3 L ablation in Pe AF. Programmed stimulation was performed to check change of ERP and RAAZ after endpoint in two AF groups.Results: Different stimulation made no significantly different AF inducibility in control group. PV stimulation made higher inducibility than CS stimulation in PAF and Pe AF groups. PV inducibility of PAF group was higher control group. There was no difference in CS inducibility between two groups. no matter CS or PV stimulation, inducibility of Pe AF was higher than control and PAF group. 2.In multi-location of atrium, ERP prolonged and RAAZ decreased after ablation. Meanwhile, AF inducibility decreased significantly. 3. Sometimes, obviously prolonged LA-PV interval could be observed during PVI. Intra-PV iducibility significantly decreased after PVI treatment.Conclusion: Because of slow and complex conduction near pulmonary vein antrum, intra-PV, inter PV, between multi-location of LA and PV, with decreased ERPPV and increased dispersion, obvious anisotropic conduction appear in LA, especially in PV and PV antrum, forming multiple and unstable reentrant loop, causing stable RAAZ, which trigger and drive AF. These changes were more obvious in PV(except RIPV) of AF patients. Most properties were similar between Pe AF group and PAF group, but more obvious in Pe AF group. Inducibility of AF is accordant with the electrophysiological difference among portions. CPVI treatment could change the electrophysiological properties of atrium in AF patients, decreasing AF inducibility.This study also found some special electrophysiological phenomena, revealing that the mutual conduction and interaction between PV and LA(especially the reentrant mechanism based on anatomy and definite electrophysiological properties) were closely related to AF mechanisms, and played an important part in the AF inducing and treatment. Considering the multiple and divergent AF mechanisms, and progressive myocardial remodeling, complete CPVI is necessary for the long-term effects of ablation.