ATRIAL ELECTROGRAM CHARACTERISTICS IN PATIENTS WITH AND WITHOUT ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

Background Multicomponent atrial electrograms and ''slow pathway poten tials'' are helpful in identifying target sites for radiofrequency cat heter ablation of the slow pathway in patients with atrioventricular ( AV) nodal reentrant tachycardia. The purpose of this study was to comp are the atrial electrograms recorded at various locations in the right atrium in patients with and without AV nodal reentrant tachycardia to assess the specificity of multicomponent atrial electrograms and poss ible slow pathway potentials both for the posteroseptal right atrium a nd for patients with AV nodal reentrant tachycardia. Methods and Resul ts In 25 patients with AV nodal reentrant tachycardia and 23 control p atients without AV nodal reentrant tachycardia or dual AV nodal physio logy, atrial electrograms with an AV ratio of less than or equal to 1: 2 were recorded at the posteroseptal right atrium near the coronary si nus ostium and in the right atrium near the posterior, lateral, and an terior aspects of the tricuspid annulus. Attempts were made to identif y broad, multicomponent, and double atrial electrograms. There were no significant differences between the patients with and without AV noda l reentrant tachycardia in the mean number of deflections in the atria l electrograms or in the mean duration of the atrial electrograms reco rded at any of the atrial sites. In all patients, the number of atrial electrogram deflections and the atrial electrogram duration were sign ificantly greater at the posteroseptal position than at the other thre e atrial sites. The prevalence of potentials with the appearance of sl ow pathway potentials in the posterior septum was similar in patients with and without AV nodal reentrant tachycardia (68% and 70%, respecti vely). The prevalence of these potentials was 6% to 25% at the other t hree atrial sites (P<.005 compared with the posterior septum). Conclus ions The atrial electrogram characteristics that have been found to be useful in identifying effective posteroseptal slow pathway ablation s ites in patients with AV nodal reentrant tachycardia are equally preva lent in patients without AV nodal reentrant tachycardia or dual AV nod al physiology. Atrial electrograms in the posteroseptal area are broad er and contain more deflections than at other areas in the right atriu m, possibly because of conduction properties of the posterior transiti onal zone that are independent of the presence of AV nodal reentrant t achycardia.