13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-45

Transmural dispersion assessed from Holter recording: a new approach to detect repolarization abnormalities in patients with inducible ventricular tachycardia after myocardial infarction

A. Lubinski, M. Kempa, E. Lewicka-Nowak, A.M. Baczynska, G. Swiatecka.
II Department of Cardiology, Medical University of Gdansk, Poland

Introduction

Reentrant activation is the most common mechanism for ventricular arrhythmias. There is evidence from several studies that increased dispersion of repolarization may create the electrophysiological condition for reentry^1-3. Dispersion of repolarization is usually attributed to regional differences in action potentials duration in different regions of heart or to dynamic changes in repolarization in consecutive beats. Recently Antzelevitch⁴ demonstrated that dispersion in repolarization may arise from differences in action potential duration between cells originating from different myocardial layers. He demonstrated the presence of M-cells characterized by the prolonged repolarization in comparison to epicardial or endocardial layers. The data from this experimental study showed that delayed repolarization of M-cell residing in midmyocardium contributes to duration and morphology of the terminal portion of the T-wave. In studies performed in the isolated perfused canine wedge⁵ the peak of the T-wave in transmural ECG was found to reflect the complete repolarization of the epicardium. Initial descending limb of the upright T-wave was shown to be related to repolarization of endocardium, while the full repolarization of the M cells marks the end of the T-wave. Evidence for the existence of M-cells in the human heart was recently provided by Drouin et al⁶ and Li et al⁷. Basing on above observation Antzelevitch⁸ hypothetized that time interval between the peak and the end of theT-wave represents the transmural dispersion of repolarization and therefore can be the important electrocardiographic index.

Since sustained ventricular tachycardia occurrence is known to be associated with increased spatial dispersion of repolarization³ we attempted to evaluate the transmural dispersion in repolarization in patients with inducible sustained ventricular tachycardia and remote myocardial infarction (VT group).

The present study aims to assess the duration of terminal portion of the T-wave in patients with inducible VT from Holter recordings and compares it with values obtained in the control group.

We performed standard 24-hour ECG recordings on magnetic tape routinely used in clinical practice in order to proof if it is possible to detect disease-related changes in transmural dispersion of repolarization.