ANALYSIS OF THE INTRAVENTRICULAR ELECTROGRAM FOR DIFFERENTIATION OF DISTINCT MONOMORPHIC VENTRICULAR ARRHYTHMIAS

This study investigated the effectiveness of correlation wave-form ana lysis for identifying different ventricular electrogram morphologies o f multiple VTs in the same patient. Patients with implantable antitach ycardia devices are commonly subject to the occurrence of more than on e distinct monomorphic VT. Each of these VTs may have unique therapeut ic alternatives for termination. VTs with identical and different mono morphic configurations were recorded (1-500 Hz) using distal bipolar ( 1 cm) and distal unipolar electrograms from the right ventricular apex . Thirty-six distinct monomorphic VTs induced in 15 patients were anal yzed. Nine VTs with identical morphologies (12/12 surface ECGs) were i nduced twice and used as a control. A template wets created for each V T induced. Correlation waveform analysis was used to compare each depo larization of all other VTs induced subsequently in the same patient. The mean correlation coefficient (rho(mu)) of cycle-by-cycle analysis was used as a discriminant function: rho(mu) greater than or equal to 0.95 was considered matched; and rho(mu) < 0.95 was considered distinc t. From the control population, VTs were successfully classified as id entical in 9 of 9 cases (100%) using both bipolar and unipolar electro grams. VTs with different monomorphic configurations were successfully classified as being different in 31 of 33 cases (94%) using bipolar e lectrogram analysis and in 29 of 33 cases (88%) using the unipolar. Te mplate matching is effective for detecting: (2) the recurrence of VTs, which are identical; and (2) the occurrence of a VT with a different configuration. This method appears effective using either unipolar or bipolar intracardiac waveforms.