Zero-fluoroscopy Catheter Ablation Of Idiopathic Premature Ventricular Contractions From The Ventricular Outflow Tract(OT-PVCs)

Background:Ventricular premature contractions(VPCs) are the most common arrhythmia in clinical practice, Moreover idiopathic ventricular tachycardia (VT) most commonly arises from the ventricular outflow tract premature ventricular contractions(PVCs) originating from the myocardium around the ventricular outflow tract are known as idiopathic ventricular arrhythmias not associated with structural heart disease, Radiofrequency catheter ablation is an effective and safe treatment for frequent symptomatic drug refractory monomorphic premature ventricular contraction. In 2006 AHA/ACC/ESC guidelines for the prevention and treatment of arrhythmia and sudden cardaic death in the treatment of symptomatic frequent monomorphic ventricular premature complexes, drug treatment is invalid or cannot be tolerated by drug or unwilling to long-term medication of patients classified as RF ablation treatment Ⅱ class a indication. But conventional tachyarrhythmia radiofrequency catheter ablation(RFCA) must be guided with X-ray fluoroscopy, This determines conventional catheter ablation is associated with relatively high exposure to ionizing radiation; This radiation exposure can be harmful to professionals and patients. So Complete elimination of fluoroscopy during catheter ablation would hence be advantageous if patient safety is not reduced; In recent years, non fluoroscopic 3-dimensional electroanatomical mapping systems have been developed to guide mapping and ablation during RFCA procedures, The Carto3 system allows visualization of the catheters used in ablation procedures without the need for fluoroscopy, Different studies have shown that the use of these systems dramatically reduces radioscopy time even zero-fluoroscopy during ablation for supraventricular tachycardia, atrial flutter, and atrial fibrillation; It allows for elucidation of detailed individual variations in anatomy and electrogram distributions, and has the ability to "tag" important sites, such as catheter locations and lesion sites, which can be revisited with great accuracy. The system can create "shadows" of the catheters, which can be used for repositioning of the catheters in the case of dislodgment. The purpose of our study was to assess the feasibility and effectiveness and safety of a complete nonfluoroscopic approach to RFCA of OT-PVCs using electroanatomical system (CART03) vs the conventional fluoroscopy-guided catheter ablation.Objective:The purpose of this prospective study was to compare the safety, feasibility, and efficacy of a completely nonfluoroscopic approach to RFCA of idiopathic premature ventricular contractions from the ventricular outflow tract(OT-PVCs) using the CART03 and ablation procedures performed under conventional fluoroscopic guidance.Study population and method:Study patientsFrom April 2014 to October 2015, We prospectively studied a consecutive series of 84 patients who admitted in Nangfang hospital for OT-PVCs ablation. All patients were divided in two groups:group A consisting of 35 patients, who treated by zero-fluoroscopy catheter ablation under the electroanatomical system (CART03) guidance, and group B consisting of 49 patients who underwent the ablation procedure guiding only by fluoroscopy, We performed a 12-lead surface ECG,24 h Holter monitoring, and two-dimensional echocardiography on each patient before RFCA; In all the patients, A 24-Holter recording demonstrated PVC burden >10%/day; There was no echocardiographic evidence of structural heart disease in any of the patients.Electrophysiologic study and RFCA procedureElectrophysiologic study:All antiarrhythmic drugs were discontinued for more than at least five half-lives prior to the study in all cases;When few spontaneous VPCs were observed at the beginning of the electrophysiologic study, A quadripolar catheter was introduced from the right femoral vein and placed in the right ventricular apex for programmed electrical stimulation or an isoproterenol infusion was performed to induce the PVCs, Activation mapping was to identify the earliest site of ventricular activation. Pace mapping was performed at a pacing cycle length of 500 ms at an output twice the diastolic threshold. The perfect pace mapping was determined from the R/S ratio and notch of the R wave in the 12-lead electrocardiogram.Electrophysiologic study proved that all the patients major VPCs originating from the ventricular outflow tract (VOT)Conventional fluoroscopic RFCA:Conventional activation and pace mapping with fluoroscopic guidance were then performed using a 4-mm tip ablation catheter inserted through the right femoral vein to the RVOT or inserted through the right femoral artery to the LVOT. The optimal ablation site was defined as the site where an identical match was necessary in at least 11 of 12 leads and if it was the site of earliest activation, The RFCA was performed based on the arrhythmia focus with a target temperature of 55 to 60℃ and a power of 30W;When an acceleration or reduction in the PVCs was observed dramatically during the first 10s of the application, the radiofrequency delivery was continued for 60 to 90s.CARTO3 mapping-guided zero-fluoroscopy ablation:In the group A. All the electrophysiologic study and RFCA procedure using CARTO3 mapping-guided zero-fluoroscopy; The system allows simultaneous visualization of all catheters used (diagnostic and therapeutic), All of the catheter’s movements were guided using the CARTO3 system exclusively. All of the medical and nursing staff worked without radiological protection from the beginning of the procedure to the end of the procedure. First the IVC-right atrial junction and the SVC-right atrial junction were marked on CARTO3, Next, the tricuspid valve was marked on the geometry, Last we created a 3-dimensional reconstruction of the cardiac right ventricular outflow tract under the guidance of CARTO3, Creation of an adequate3D image of the RVOT could be completed or created a 3-dimensional reconstruction of the cardiac left ventricular outflow tract in several minutes. Activation mapping and pace mapping were performed during the creation of geometry procedure; The earliest activation site during the PVCs was identified from the activation map made by the electroanatomic map using the auto-freeze map. pace mapping and scoring were also performed around the earliest activation site in the same manner as in the conventional technique; And when we found the optimal ablation site. Radiofrequency energy was delivered with ablation catheter in temperature-controlled mode with a target temperature of 55℃ at a power of 30 W. If the VPBs were abolished within 20 seconds, the energy application was continued for 60 to 90 seconds.The endpoint of RFCA:After ablation, programmed ventricular stimulation and isoproterenol infusion were used to confirm the effectiveness of RFCA in all patients. Ablation was considered an acute success if no VPCs with similar morphology occurred during the a 30-minute observation period.Follow-up:All the patients were followed up for 5 to 11 months, The 24h Holter monitor was repeated 3 months post ablation; a decrease of　>80%　in the PVC burden was defined as a successful outcome. Recurrence was defined OT-VPC burden did not have a decrease of　>80%　after the RFCA.Statistical analysesData are reported as means ± standard deviations (SDs), Continuous variables were compared by using an independent sample t-test. and using the chi-square test, corrected by the Fisher exact test when necessary, for categorical variables. Statistical packet SPSS version 20.0was used for all of the calculations. A value (2 tailed) of P<0.05 was considered statistical significant.Results:A total of 84 ablation procedures were performed during the study period, we enrolled 35 patients in Group A (ablation without fluoroscopy) and 49 patients in Group B (conventional ablation);Patient characteristics:Distributions of gender, age were not significantly different between the two groups. There was no significant difference between the VPC burden and VPC site of origin of patients who underwent nonfluoroscopic catheter ablation (Group A) compared to the patients who underwent catheter ablation with fluoroscopic guidance (Group B)Procedural data:There was no significant difference in the acute success rate of ablation between the zero-fluoroscopy group and the conventional group(34/35 [97.1%] vs 44/49 [89.8%] p= 0.393),No major complications observed during the procedures in either group. Despite the additional time required to set up the non fluoroscopic system and to create the three dimensional geometry, Patients in the group B required a longer total procedure duration compared to the group A(74.8±10 vs 67±11.9min p=0.002). the procedure was completed without any fluoroscopy use in the group A; While Mean fluoroscopy time for the group B was 18.6±6.8 minutes。 The group A showed a shorter mapping time compared to the group B(4.3±1.9 vs 7.0±2.4 min p<0.01); The group A exhibited significantly fewer number of RF applications and than the group B (4.8±1.9 vs 6.6±1.7 p<0.01),There was no significant difference in the recurrence rates between the two groups over a follow-up period of 5 to 11 months.Conclusion:Catheter ablation for OT-PVCs without fluoroscopic guidance is feasible and safe, and it can shorten the total procedure time and the mapping time, it also can reduce the number of RF applications. The elimination of radiation exposure is considerable for patients and professionals.