The goal of this clinical trial is to make clear that a new method, right ventricular outflow tract (RVOT) posterior septum pacing, has a greater accuracy in predicting the origin of ventricular outflow tract (VOT) ventricular arrhythmias (VAs) compared to the previous electrocardiographic standards for the identification of the origin of ventricular outflow tract. The secondary aim is to investigate, by using the new method, if it can optimize the procedure of radiofrequency catheter ablation. Researches will break the method of this investigation into two steps: First step have enrolled 100 patients. This step would be used to compare the results predicted by right ventricular outflow tract posterior septum pacing, with the previously used electrocardiographic criteria and actual target site. The second step will enroll another 100 patients. In this step, patients will be divided into two groups, one being the new protocol group and the other being the convention group. Patients will also be followed up, for 1 month and 3 months at outpatient clinic post procedure. Procedure time, success rate, fluoroscopy exposure time and complications, are compared between RVOT posterior septum pacing group and convention group.