Guiding Function Of Visual Unipolar Electrograms In Catheter Ablation For Outflow Tract Idiopathic Ventricular Arrhythmia By Ensite Array System

Objective Mapping the origin of outflow tract ventricular arrhythmia by Ensite Array system to analyse its virtual unipolar electrogram (VUEs) features and its guidance for catheter ablation.Methods54patients who were accepted radiofrequency ablation by means of non-contact mapping system for ventricular arrhythmia in the electrophysiology laboratory of the Second Xiangya Hospital of Central South University from Jan.2013to Apr.2014were recruited. According to the target position in the course of radio frequency ablation, the patients were devided into non RVOT endocardial group (n=8) and RVOT endocardial group (n=45), whose characteristics of the VUEs were analysized, including the earliest site to QRS onset time (EA-QRS time), breakout site to QRS onset time (BO-QRS time), distance between the earliest site to the breakout site (EA-BO distance), time interval between the earliest site to breakout site (EA-BO time), virtual unipolar voltage amplitudes of the initial negative slope of the earliest site and breakout site at time phases of3and6ms. In addition, related parameters of VUEs in the RVOT group were analysized combined with radiofrequency ablation for X-ray exposure time and operation time.Results1. EA-QRS time and BO-QRS time:non RVOT endocardial group were shorter than RVOT endocardial group (P＜0.05); EA-BO time and EA-BO distance:non RVOT endocardial group were longer than RVOT endocardial group (P<0.05); the EA3ms, EA6ms voltage: non RVOT endocardial group was less than RVOT endocardial group (P＜0.05); the BO3ms, BO6ms voltage:the two groups were not statistically significant (P>0.05). The sensitivity of BO-QRS time≥12ms predition RVOT endocardial origin was93.3%, the specificity was100%.2. While the RVOT endocardial group was divided into two groups according to the median value of the EA6ms voltage (0.62mV), the group with an EA6ms voltage<0.62mV required a greater total X-ray exposure time and operation time (P<0.05).Conclusions1. Ensite Array system for outflow tract ventricular arrhythmias in three-dimensional mapping is safe and effective.2. The virtual unipolar electrograms could help to identify the RVOT endocardial origin and non RVOT endocardial origin of ventricular arrhythmia.3. The virtual unipolar electrograms help to indicate the degree of difficulty of radiofrequency ablation therapy.