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A major cause of inappropriate treatment delivery by current implantable antitachycardia devices (ATDs) is failure to distinguish between paroxysmal ventricular tachycardia (VT) which requires therapy and supraventricular tachycardia (SVT) for which therapy should be suppressed. Proposed solutions to address this problem, such as morphological analysis of intracardiac electrograms, will also fail in the case of aberrantly conducted SVT. Examining the onset sequency of an arrhythmia has been proposed as an alternative for distinguishing VT from SVT. Such sequency analysis is based upon the hypothesis that VT commonly starts with one or more ventricular premature depolarizations (VPDs). Twenty-six spontaneous tachyarrhythmia onsets from 21 patients with simultaneous intraatrial and intraventricular recordings or simultaneous esophageal (atrial) and surface (ventricular) recordings were processed for interpretation of SVT and VT. The diagnosis of VT was made for onsets containing one or more VPDs; otherwise SVT was diagnosed. The algorithm diagnosed 7/7 VTs for 100% sensitivity. Specificity was 16/19 or 84%. Three cases of SVT were misdiagnosed as VT. >

New techniques of arrhythmia detection using morphology of the waveform have shown promise in correctly detecting fatal arrhythmias. Morphologic analysis of two channels, atrial and ventricular, has the potential of improving the ability of the algorithm to distinguish arrhythmias. This study uses correlation waveform analysis of intracardiac electrograms from the right ventricular apex and the high right atrium to define a two dimensional feature space with linear decision boundaries created from a training set by a least squares minimum distance classifier. The total set represented 16 patients. This method correctly discriminated 48/48 cycles of sinus rhythm, 47/48 of ventricular tachycardia (VT), 39/48 of atrial tachycardia and 40/48 of VT with retrograde, and supraventricular tachycardia with aberrant conduction. Performing this technique on two intracardiac electrograms appears to reliably differentiate various arrhythmias and warrants further study. >