A Research On The Efficacy And Safety Of Modified Anatomical Substrate Based Ablation Approach Of Verapamil-sensitive Idiopathic Left Ventricular Tachycardia

Background:Idiopathic left ventricular tachycardia(ILVT),also termed as verapamil-sensitive ventricular tachycardia,given its characteristic termination by verapamil infusion,occurs predominately among young people in the absence of apparent structural heart disease.Corresponding to its left ventricular origin,ILVT shows a right bundle branch block morphology with either left axis deviation and a left anterior fascicular(LAF)block QRS complex pattern.Left posterior fascicular(LPF)accounts for the most common original site of ILVT and the exact mechanism are not well illustrated.Currently,ILVT is only amenable to cure through radiofrequency catheter ablation.However,the ablation strategies and its success rate are various.Objective:The purpose of this study was to discuss the efficacy and safety of catheter ablation of idiopathic left Ventricular Tachycardia(ILVT)during sinus rhythm basing on anatomical substrate and long-term effects.Methods:Between October 2012 and December 2016,a total of 31 consecutive patients with verapamil-sensitive ILVT exhibiting a right bundle branch block(RBBB)configuration and left-axis deviation underwent modified anatomical substrate based ablations were included in our research.Echocardiography,chest X-ray and cardiac enzymes were performed in order to rule out structural heart disease.Coronary sinus,right ventricular apex(RVA)and His electrodes were introduced through left subclavian vein and right femoral vein after local anesthesia.Electrophysiology study were conducted to exclude atrioventricular nodal dual pathway and atrioventricular accessory pathway.Then right femoral artery was punctured,and Johnson&Johnson Navistar catheter were introduced retrograde to the left ventricle to construct a three-dimensional geometry model.His,left bundle,LAF and LPF region were mapped during sinus rhythm and low voltage areas were excluded.The activation mapping procedure was performed along the LPF region where Purkinje potentials(PP)characterized by high-frequency and sharp potential before QRS complex were recorded.radiofrequency current applied to the posterior portion of left ventricular septum showing PP was delivered using a temperature-controlled mode 53?/35W until the PP demise or apparent decreased.12 leads-ECG,24h Holter recording and echocardiography were obtained at the first,third,sixth twelfth months follow up and at about six-month intervals.Results:31 patients concluded in this research contained 19 men and 12 women,mean age 29.9±14.0 years old.Seven of the 31 patients had previous unsuccessful ablation attempts with detected recurrent ILVT.The mean episodes of tachycardia was 8±6 times with 2±0.5 hours duration time.No severe complications were reported during or post ablation.Over a mean 41±22 month follow-up period,without administration of any anti-arrhythmic drug,none reported recurrent VT and the mid-success rate is 100%.Ablation time 46.7±11.3 minutes,radiation exposure dose8.7±2.1mGy,ablation area2.8±0.7 cm2,RFCA time 11.50±4.24 minutes,width of QRS pre-ablation was 80-120(99.69±11.25)ms compared with 88-120(99.38±10.05)post-ablation both during sinus rhythm,Left diastolic diameter 41.50 ±4.29mm before compared with 41.81 ±3.73mm post ablation,left ventricular ejection fraction 58.44±5.68%before compared with 58.71 ±4.21%post ablation.The width of QRS,left ventricular diastolic diameter,ejection fraction before and after ablation showed no statistically significant(P>0.05).Fourteen patients(approximately 45%)demonstrated LPF block while the rest showed no block.Conclusion:As for ILVT,anatomical substrate based modified ablation proved a success,whether with history of the ablation attempts with high successful rate and efficacy.No ECG and heart function effects were observed.