Identification of Ventricular Tachycardia Using Intracardiac Electrograms: A Comparison of Unipolar Versus Bipolar Waveform Analysis

Abstract

Implantable antitachycardia devices suffer a high false-positive rate of delivery of therapy because current detection schemes based upon ventricular rate and rate variations are excessively sensitive at the cost of specificity. Several methods have been proposed for providing complementary information derived from morphologic analysis of intraventricular electrograms in order to increase specificity. The majority of these techniques have utilized bipolar electrogram analysis to detect changes in ventricular activation indicative of ventricular tachycardia. Whether bipolar or unipolar intracardiac electrogram analysis might be preferred for discriminating ventricular tachycardia from sinus rhythm has not been determined. In this study, a previously demonstrated method for identification of ventricular tachycardia using intracardiac electrograms, correlation waveform analysis, was used to analyze both unipolar and bipolar signals during sinus rhythm and ventricular tachycardia recorded during electrophysiology studies of 15 patients with inducible sustained monomorphic ventricular tachycardia. Correlation waveform analysis consistently discriminated between all depolarizations during ventricular tachycardia in 14/15 patients (93%) using either electrogram configuration; 13 of the 14 patients were common to both groups. Of these patients, 8/15 (53%) had greater separation between sinus rhythm and ventricular waveforms with bipolar electrogram analysis while 7/15 (47%) had greater separation with unipolar electrogram analysis. We conclude that morphologic analysis of unipolar and bipolar electrograms may be equally effective in distinguishing ventricular tachycardia from sinus rhythm. For individual patients, either a unipolar or bipolar ventricular configuration may be preferable, and should be chosen on a patient-specific basis during electrophysiology study prior to antitachycardia device implantation.

Noncontact Mapping of the Left Ventricle:

“…Agreement of waveform morphology between the noncontact and contact electrograms was quantified using Pearson's correlation coefficient 15–17 . Perfect agreement corresponded to a correlation of 1, with 0 indicating no association.…”

Automated Ventricular Substrate Mapping—Evaluation in an Ovine Chronic Myocardial Infarction Model

“…Pearson's correlation is a well-recognized pattern matching methodology that has been shown to be useful for analyzing electrogram data in the previous studies. 18,19 Again, the inherent data redundancy made it theoretically advantageous to use a high correlation value (R > 0.95) that maximized specificity at the expense of sensitivity. To construct the scar maps we used the same correlation value across all of the studies to improve the scientific validity of this evaluation.…”

“…The ASM program then compared each beat within the data file with the reference beat using Pearson's correlation. [18][19][20] Segments from the two beats (500-ms length), were aligned using the time of the maximum slope within the reference channel. The best lag-shifted correlation for each beat was written to the data index.…”

Use of Correlation Waveform Analysis in Discrimination Between Anterograde and Retrograde Atrial Electrograms During Ventricular Tachycardia

“…Follow-up studies with catheters positioned in the right atrial appendage or coronary sinus ostium might improve our understanding of the importance of the location of the recording bipole. Even though unipolar recordings are more site speci c than bipolar recordings, both have been shown to be equally effective in distinguishing VT from SR. 7 Atrial catheters can move when VT is induced. Even though this was not grossly documented by uoroscopy, microdislodgments could not be ruled out.…”