DISCRIMINATION OF SINUS RHYTHM, ATRIAL-FLUTTER, AND ATRIAL-FIBRILLATION USING BIPOLAR ENDOCARDIAL SIGNALS

Introduction: Analysis of endocardial signals obtained from an electro de located in the right atrium as realized in newly designed dual cham ber, implantable cardioverter defibrillators might be used to provide additional therapeutic options, such as overdrive pacing or low-energy atrial cardioversion for the treatment of concomitant atrial flutter (AFL) or atrial fibrillation (AF). Therefore, we developed a computer algorithm for discrimination of normal sinus rhythm (NSR), AFL, and AF that may lead to adequate differential therapy of atrial tachyarrhyth mias in an automated mode. Methods and Results: During an electrophysi ologic study, bipolar endocardial signals from the high right atrium w ere obtained in 28 patients during sustained AFL or AF and after resto ration of NSR. A total of 286 data segments of 5-second duration were recorded (NSR: 96, AFL: 86, AF: 104). Mean atrial cycle length (R;ICL) , standard deviation of mean atrial cycle length (SDCL), and index of irregularity (IR), defined as the ratio between R;ICL and SDCL, were c alculated for each data segment. A cutoff of 315 msec for R ICL allowe d discrimination of NSR from atrial tachyarrhythmias with 100% sensiti vity and specificity. For discrimination of AF from AFL by using SDCL, a cutoff value of 11.5 msec led to a sensitivity of 99% and a specifi city of 90%. Best discrimination of AF from AFL was found for the crit erion IR greater than or equal to 7.5%, resulting in a sensitivity of 100% with a specificity of 95 % for AF detection. Conclusion: The inve stigated algorithm provides discrimination of NSR, AFL, and AF with hi gh sensitivity and specificity. Incorporation of this algorithm in an implantable automated antitachycardia device may lead to adequate diff erential therapy in patients suffering from spontaneous episodes of AF and AFL.