Objective To observe the influence of accessory pathway(AP)conduction on PJ interval in preexcitation syndrome patients.Methods 129 patients with a single manifest AP who underwent successful radiofrequency ablation(RFCA)were included.The patients were divided into 10 groups according to AP location.The PR intervals,QRS durations and the PJ intervals were measured using simultaneous 12-lead ECG before and after ablation.The PJ intervals before ablation were compared with those after ablation.The atrioventri...