New Descriptors of Homogeneity of the Propagation of Ventricular Repolarization

Abstract

BATCHVAROV, V., ET AL.: New Descriptors of Homogeneity of the Propagation of Ventricular Repolar ization. Available descriptors of irregularities of ventricular repolarization are of limited clinical value. We studied the effect of autonomie variations on several new descriptors of the three-dimensional T loop. Twelve-lead digital ECGs were recorded continuously in 40 healthy subjects at baseline in the supine po sition, during postural changes (supine -> sitting -> standing -> supine -> standing), and during Valsalva maneuver performed three times in the supine and three times in the standing positions. A minimum di mensional space was constructed from the 12-lead ECG, using singular value decomposition, on the ba sis of median ECG beats constructed from 10-second consecutive ECG recordings. Temporal variations (TLA and PL, which measure the T loop area, and LD, the interlead relationship during repolarization) and wavefront direction descriptors (TCRT, the deviation between the QRS and T vectors) were calculated and expressed as normalized values. Values of TLA, PL, and TCRT were significantly lower in the sitting than in the supine position (-38139 ± 9099 vs 47133 ± 7511, -0.017 ± 0.005 vs 0.033 ± 0.005 and -0.032 ± 0.019 vs 0.071 ± 0.015, respectively, P < 0.001 for all) and decreased further in the standing po sition (-88288 ± 14468, -0.067 ± 0.013, -0.198 ± 0.025, respectively, P < 0.001 for all). LD increased from supine to sitting (98.7 ± 29.4 vs -87.5 ± 15.2, P < 0.001) and increased further, though nonsignificantly in the standing position (118.3 ± 35.2). TLA, PL, and TCRT decreased from baseline during Val salva in the supine (-34118 ± 11424 vs 62234 ± 12215, -0.038 ± 0.014 vs 0.065 ± 0.010, -0.08 ± 0.03 vs 0.10 ± 0.02, respectively, P < 0.001 for all) and standing positions (-108263 ± 21051 vs -68909 ± 10271, -0.109 ± 0.014 vs -0.048 ±0.009, -0.30 ± 0.035 vs -015 ± 0.016, respectively, P < 0.05 for all). LD was significantly increased by Valsalva in the supine position (13 ± 46 vs -153 ± 30, P < 0.001) and nonsignificantly in the standing position (99 ± 50 vs 86 ± 30, P -NS). There were significant correlations among TLA, PL, and LD, and no significant correlation between TCRT and any of the temporal variation descriptors. These new temporal and wavefront direction descriptors are sensitive and rapid detectors of autonomie effects on ventricular repolarization. (PACE 2000; 23[Pt.II]:1968-1972 ventricular repolarization, autonomie modulation, ECG analysis

T‐Wave Morphology Parameters Based on Principal Component Analysis Reproducibility and Dependence on T−Offset Position

“…Previous studies have demonstrated autonomic influences on T-wave parameters. 34,35 In this study, the main changes were observed at 2 p.m., that is in postprandial conditions. Thus, the circadian differences in T-wave morphology parameters based on PCA may not be related only to circadian heart rate changes.…”

Dynamics and Rate‐Dependence of the Spatial Angle between Ventricular Depolarization and Repolarization Wave Fronts during Exercise ECG

“…8 However, this can be explained with posture, as supine TCRT values are larger than TCRT values measured while sitting or standing. 12 During the course of exercise, the TCRT and QRS/T values decreased toward the exercise peak, reaching negative values. Negative TCRT values are generally observed in cardiac patients, and they have been associated with poor clinical outcome.…”

Clinical Implication of T-Wave Morphology Analysis as a New Repolarization Descriptor

“…Batchvarov et al demonstrated a relationship between these descriptors and autonomic activity, 20 but the physiologic meaning is still uncertain. The concept of QT interval dispersion reflects ventricular repolarization only based on the duration of the QT interval.…”