CHARACTERISTICS OF BIPOLAR ELECTROGRAMS DURING ANTEROGRADE MAPPING - THE IMPORTANCE OF ACCESSORY ATRIOVENTRICULAR PATHWAY LOCATION

Local endocardial electrograms recorded at successful radiofrequency a blation sites during anterograde mapping (QRS-V interval, atrioventric ular [AV] interval, AV ratio, the presence of accessory pathway potent ial, and stability of atrial and ventricular electrogram) were analyze d and compared according to location of accessory pathways. The mitral and tricuspid annuli were divided into 10 regions, Endocardial electr ograms differed with regard to location of accessory AV pathways, The QRS-V interval was more negative in right posteroseptal, right free wa ll and right anteroseptal locations than the interval in other locatio ns, The AV interval was longer in posteroseptal than the interval in l eft and right free wall sites, The stability of atrial and ventricular electrograms was better in left free wall sites than in posteroseptal sites and worst in right free wall and right anteroseptal sites, The variation in local electrograms at successful ablation sites with resp ect to pathway location may partly explain the low predictive value an d the marked variation in previously suggested criteria for selecting target sites for radiofrequency energy delivery, The results also impl y that the influence of accessory pathway location must be considered when attempts are made to establish electrogram-based criteria for pre dicting successful ablation of accessory pathways.