| Objective:. The aim of the study is to propose a new and simple ECG method for the localization of right manifest accessory atrioventricular pathways. Three reasons are listed as followings. Firstly, with the extensive application of Radiofrequency Catheter Ablation (RFCA) in the treatment for the patients with symptomatic Wolff-Parkinson-White syndrome, prediction of locations of accessory pathways(APs) before the ablation procedure becomes more and more important because the ablation procedure and electrophysiologic study can be facilitated by planning the ablation technique in advance. In addition, the possibility of mechanical trauma on the pathways by the electrode catheter can be minimized if the pathways located in the susceptible regions are known before electrophysiologic study. Secondly, radiofrequency catheter ablation produces a very discrete lesion and ECG localizations based on surgical dissection which were studied before 1990's are obsolete because their electrocardiographic features at the various sites overlap to a considerable degree due to much trauma of surgical dissection, resulting in difficulties for application during RFCA. On the other hand, current ECG localization algorithms based on RFCA dissection also have some limitations such as complication, difficulties for remembering and poor accuracy on the condition of illegible delta waves and the inaccuracy of the electrode positions of horizontal plane. Thirdly, according to the experience of RFCA practitioners the ablation of right manifest accessory pathways spends more time and more energy than that of left accessory pathways. Furthermore, ECG localization of left manifest accessory pathways is almost as accurate as the endocardial mapping. These reasons instigate us to study the ECG localization of right manifest accessory pathways. We are ready to determine the sensitivity, specificity, accuracy, positive likelihood ratio and negative likelihood ratio of the new method and compare it with another two famous algorithms in order to certain its value.Methods: ECG characteristics of 86 W-P-W cases with manifest right accessory pathways,whose APs had been successfully ablated by radiofrequency, were analyzed. The leads â…¢ and aVR located in the region of tricuspid ring were found to be the most discriminating leads . Their respective sum of QRS voltage were chosen as the locating tools to form a new method for the localization of right APs. Then, the method was used to predict the locations of those 86 cases in a blinded fashion and its sensitivity, specificity, accuracy, positive likelihood ratio and negative likelihood ratio were calculated .Our new proposed method was compared with another two famous algorithms, Fitzpatrick's and Chiang's by calculating their overall accuracy, in order to evaluate its clinical values.Results: By using the new method, the sensitivity, specificity and accuracy for predicting septal and non-septal right accessory pathways were 76.7%, 86.1%, 81.4% and 88.4%, 79.1%, 83.7%; The sensitivity, specificity and accuracy for right anterior septal (RAS), right posterior septa (RPS), right anterior lateral (RAL) and right posterior lateral (RPL) were between 55.6%-88.2,89.9%-93.4%,83.7%-89.5%, respectively. Positive likelihood ratio and negative likelihood ratio were between 6.3-11.6 and 0.13-0.49 respectively. Overall, the accuracy of our algorithm was 74.4% and there was no significant difference between ours and Chiang's algorithm(74.4% versus 79.1% , p>0.05),but our algorithm's overall accuracy is higher than that of Fitzpatrick(74.4% versus 61.6% , p<0.05).Conclusion: Previous ECG localization methods had some limitations such as poor accuracy, complication, vulnerability and so on. The new body surface ECG locating method composed of lead â…¢ and lead aVR is simple and accurate for predicting the localization of right manifest accessory pathway. It is also proved that lead aVR ignored by most studies has some use in locating the accessory pathway and deserves more concern and investigation.
|
PDF Full Text Request