The process of repolarization of ventricular myocardium in patients with Wolff-Parkinson-White syndrome

Radiofrequency ablation of accessory atrio ventricular conduction pathways is at present the preferable method of nondrug treatment of Wolff-Parkinson -White (WPW) syndrome. This procedure can be associated with ECG changes. U nderstanding of features of processes of ventricular de- and repolarization characteristic for WPW syndrome is required for correct identification of these postablation ECC changes. Anomalous process of depolarization caused by the presence of accessory atrioventricular conduction pathways is consid ered to be well studied electrophysiological phenomenon. The aim of this st udy was to find out whether some special features of myocardial repolarizat ion also exist in manifested WPW syndrome and whether they persist after ch ange of sequence of myocardial excitation. Data of surface ECC mapping of 1 12 patients with manifested and intermittent WPW syndrome obtained before a nd after ablation of variously located accessory conduction pathways and al so of patients subjected to ablation because of other supraventricular arrh ythmias were used for this purpose. It has been shown that in manifested WP W syndrome there exists an abnormality of ventricular repolarization the se verity of which depends on location of accessory pathways and in parietal p athways - on degree of preexcitation. In paraseptal anterior and posterior accessory pathways the process of repolarization of ventricular myocardium is opposite to the process of depolarization and values of difference of co rresponding electrical axes might serve as complimentary diagnostic tool fo r determination of location of an anomalous conduction pathway and in diffe rential diagnosis of paraseptal and parietal accessory pathways. Similar ra diofrequency energy applied to the myocardium caused more pronounced abnorm alities of repolarization in patients with manifested preexcitation syndrom e. These abnormalities were predominantly due to anomalous process of myoca rdial depolarization. In patients with all except right-sided accessory pat hways immediately after radiofrequency ablation locations of maximal and mi nimal values of ST integral on surface ECG coincided with maximal and minim al values of delta wave before the procedure.