Abstract: Abstract Objective:To investigate the law and the reason of the electrotonic modulated T wave(EMTW) after radiofrequency ablation(RFCA) in patients of preexcitation syndrome.Methods:By observing the EMTW in ECG before and immediately after RFCA in 109 cases who had preexcitation syndrome,to conclude the law of EMTW in position and amplitude.Rusults: EMTW were detected in in 78 of the 109 cases,the rate of EMTW is more lager in right free wall、right posterior septal、right posterior free wall、left anterior free wall、left free wall than other positions,and the EMTW is not only inverted.Conclution:The position and amplitude of the EMTW is relative with the positions of the pathway.

Key words: preexcitation syndrome, radiofrequency ablation, lectrotonic modulated T wave, achycardia, ardiac memory