Objective:To analyze surface electrocardiogram features of patients with ventricular arrhythmias arising from different outflow tracts.Methods:102 patients with ventricular arrhythmias were enrolled in this study.All of them underwent standard 12-lead electrocardiography.Electrocardiogram features and parameters of patients with ventricular arrhythmias arising from different ventricular outflow tracts and different positions of pulmonary valve in the right ventricular outflow tract were recorded.Results:All patients in-cluded in this study showed positive R waves in inferior wall leads on surface electrocardiograms,and QS pattern in aVL and aVR.A-mong the 102 patients,there were 19 cases with left ventricular outflow tract arrhythmias and 83 cases with right ventricular outflow tract arrhythmias,including ventricular arrhythmias arising above pulmonary valve(n=44)and below pulmonary valve(n=39).R wave amplitude,shortest RS(SRS),and intrinsicoid deflection time(IDT)in the right ventricular outflow tract group were smaller and shor-ter than those in the left ventricular outflow tract group(P<0.05).For patients with ventricular arrhythmias arising from different posi-tions of pulmonary valve in the right ventricular outflow tract group,R wave amplitude in lead II and lead aVF in the above pulmonary valve group was greater than that in the below pulmonary valve group,while RⅢ/RⅡwas lower than that in the below pulmonary valve group(P<0.05).There were statistically significant differences in QRS duration,R wave amplitude in lead III and aVF,Q wave am-plitude in lead aVL,and RⅢ/RⅡ among patients with ventricular arrhythmias originating from different anatomical parts of pulmonary valve(P<0.05).QRS duration in the right sinus group was longer than that in the left sinus group.The R wave amplitude in lead Ⅲ and aVF,Q wave amplitude in lead aVL and RⅢ/RⅡwere smaller than those in the left sinus group and the anterior sinus group.The Q wave amplitude in lead aVL was smaller than that in the left and right sinus junction group(P<0.05).R wave amplitude in lead Ⅲ and aVF in the left sinus group was greater than that in the left sinus junction group(P<0.05).Conclusion:Patients with ventricular arrhythmias arising from different outflow tracts have different surface electrocardiogram features and parameters.Clinically,the outflow tract where ventricular arrhythmias originate can be determined by relevant surface electrocardiogram parameters.