AUTOMATED-ANALYSIS OF SPONTANEOUSLY OCCURRING ARRHYTHMIAS BY IMPLANTABLE DEVICES - LIMITATIONS OF USING RATE AND TIMING FEATURES ALONE

Real-time automated systems for arrhythmia analysis by implantable ant itachycardia devices have been designed to incorporate two-channel rat e criteria with intracavitary atrial and ventricular electrogram morph ology. Because the power requirements for morphologic analysis substan tially limit antitachycardia device longevity, the authors sought to d evelop an alternative algorithm that relies solely on rate and three n ewly developed timing features: onset (median ventricular rate filteri ng to detect abrupt onset), loss of atrioventricular (AV) sequency (pr emature ventricular depolarizations), and regularity-multiplicity (min imal median cycle length variation concurrent with integral [n:1] AV p eriodicity). This system was assessed using spontaneously occurring ar rhythmias in patients undergoing electrophysiology studies. Electrogra ms were captured on FM tape (1-500 Hz) using bipolar catheters in the high right atrium and the left ventricular apex. In 11 patients, 25 di stinct arrhythmias were analyzed, which included sinus tachycardia (ST ) (1 passage), supraventricular tachycardia (SVT) (6 passages), ventri cular tachycardia (VT) with concurrent sinus rhythm (16 passages), VT with concurrent atrial flutter (VT/AF1) (2 passages), and ventricular fibrillation (VF) (I passage). The algorithm correctly diagnosed 1 of 1 episode of ST, 4 of 6 episodes of SVT, 15 of 16 episodes of VT with concurrent sinus rhythm, 0 of 2 episodes of VT/AF1, and 1 of 1 episode of VF. Ventricular tachycardia episodes were misdiagnosed as SVT beca use of absence of loss of AV sequency in VT onset (1 episode), presenc e of multiplicity between VT and AF1 (1 episode), and absence of VT re gularity during AF1 (1 episode). Algorithms that are confined to rate and timing features alone are capable of correctly diagnosing most spo ntaneously occurring tachyarrhythmias. Misdiagnosis of VT may occur, h owever, despite the integration of multiple timing features.