We studied the influence of the heart position in the thorax on the autocorrelation (AC) maps consisting of correlation coefficients between each pair of instantaneous electrocardiogram potential distributions over a time interval. We used a thorax-shaped electrolytic-filled tank with an isolated and perfused dog heart placed at positions spanning 5 cm on each space direction. The correlation coefficient between QRST AC maps was in the range of 0.92

The T wave complexity can be studied using multiple thoracic leads (surface potential maps) or the 12-lead ECG. Body surface potential maps (BSPM) have two major advantages over the conventional 12 leads: to explore the entire chest surface and to be more sensitive in detecting local electrical events. On the other hand, the method of BSPM is impractical for wide clinical use. Different methods of analysis of BSPM have been used to study repolarization

Diferente legate de sex in stabilitatea distributiei potentialelor ECG pe suprafata corpului in timpul repolarizarii ventriculare. La femei, situatiile asociate cu prelungirea intervalului QT sunt insotite de un risc mai mare de aparitie a aritmiilor ventriculare maligne cum este torsada varfurilor. Obiectivul acestui studiu a fost evaluarea diferentelor legate de sex in repolarizarea ventriculara, folosind transformari ale semnalelor electrocardiografice

We computed and compared autocorrelation maps (AC maps) from ECG recordings obtained on human thorax shaped electrolytic filled tanks in which a perfused dog heart was immersed at various geometrical displacements (in a range of 5--6~cm on $x$, $y$ and $z$), by considering the correlation between instantaneous potential distributions at each pair of instants over the QT interval. The correlation coeficient between AC maps was in the range of 0.92--0.99

The purpose of this study was to explore the link between various types of repolarization heterogeneities and electrocardiographic indices previously proposed for estimating them. Models of both ventricles with a spectrum of values for transmural gradient of action potential duration (APd), longitudinal gradient and interventricular gradient were generated as well as localised changes of APd in the free left ventricular wall. A spherical lead system

Theoretically, under certain assumptions, correlation coefficients between ECG potentials at different instants on the same electrodes would not depend on the electrode system. We simulated ventricles surrounded by various 192-lead spherical electrode systems in a homogenous unbounded volume conductor. Autocorrelation maps of the simulated ECG on each lead system were obtained with the same activation and repolarization. Differences between the autocorrelation

BACKGROUND: Left ventricular hypertrophy (LVH) is accompanied by specific changes in ventricular electrophysiology, which are potentially arrhythmogenic. Nevertheless, the electrocardiographic diagnostic signs for LVH have a relatively low predictive power for arrhythmic events and sudden death. We thought that other parameters derived from the surface ECG, not apparent at visual inspection, might be detected by specific analysis of electrocardiographic