Study On The Diagnostic Value Of Different Doppler Tissue Imaging Mode Localizing Arrhythmia Site

Part I .The accuracy of different Doppler tissue imaging modes localizing early ventricular contraction associated with accessory pathways in Wolf-Parkinson -White Syndrome Background: Recent advances in transcatheter techniques with radiofrequency enabled the ablation of the accessory atrioventricular pathways in Wolff-Parkinson-White (WPW) syndrome since 1990.At the time of the ablation treatment, accurate localization of the manifest accessory pathways(MAP) is of primary importance.A standard electrocardiogram with 12 leads and echocardiography are used to determine the early activation sites noninvasively.However, pinpoint localization of the MAP still seems to be difficult. Tissue Doppler Imaging (DTI) technique in which ventricular wall motion is coded by color is applicable for the quantitative assessment of ventricular wall motion.But,the accuracy and feasibility of different DTI in the localization of the accessory atrioventricular pathways in WPW syndrome remain unclear. Objective This study sought to investigate and compare the feasibilityand accuracy of different DTI modes for predicting the accessory pathway localization in patients with WPW syndrome. Methods Before radiofrequency catheter ablation (RFCA),60 patients with WPW syndrome were studied by DTI.2D-DTV and DTA were used for the localization of the earliest activation bright spot appearing on the endocardial side. M-DTV and PW-DTV were used for the evaluation of the shortest electromechanical time interval (AT) .AT were measured from the onset of the delta wave to the beginning of the ventricular systolic motion. The earliest contraction or MAP site was defined as the site demonstrating the shortest AT and the earliest bright spot. Then the earliest contraction site was compared with the earliest activated site determined by the successful ablation site. The result of electrophy-siological study (EPS) was used as a standard .Results The shortest mean AT and the earliest bright spot were found at the middle septum in control subjects and at the AP site in WPW patients . The mean AT was observed at the AP site ( 29.3 11.9ms ) andat the middle septum (56.7 15.2ms)by PW-DTV in WPW patients.Thecorrelation of M-DTV and PW-DTV was good. The MAP could be.precisely localized in 65% of the patients by 2D-DTV,in 75% by 2D-DTA,in 67% by M-DTV,in 68% by PW-DTV and in 86% by a combination of the four modes respectably.After the successful RFCA,the bright spots and the time difference were found to disappear by DTI in allpatients.Conclusions DTV and DTA were more directly viewed,while M-DTV and PW-DTV were more accurately for the time,pace.DTI-determined earliest contraction sites were well coincided with the sites of the MAP determined by the EPS.The DTI, especially when used in combination of the four modes is helpful to localize the MAP and to evaluate the results after RFCA objectively, accurately and non-invasively.The technique might be as a complementary of the EPS and of considerable value clinically.