Normal ventricular repolarization dispersion range with abrupt heart rate changes

Abnormal alterations in ventricular repolarization dispersion (VRD) have been shown to constitute a substrate for arrhythmias. In this work, we have induced abrupt heart rate (HR) changes to 17 healthy subjects through a Tilt-test Maneuver and have analyzed the evolution of several VRD indices. Duration ones, based on ECG intervals; complexity ones, developed through a Principal Components Analysis in T-wave; and the amplitude one, extracted feature from an absolute T-wave. Results have shown statistically significant decreases in T-wave onset-to-peak, finding that these changes are responsible for the alterations in the T-wave width and in the QT interval. Also, simultaneously it has been observed that T-wave peak-to-end has not shown statistical significance. Moreover, we have found statistically significant decreases and increases of the ratio of the 2nd to the 1st eigenvalue in early and late T-wave respectively. On the other hand, from measurement response times, we have observed that the shape of the T-wave undergoes to a fast initial reduction in amplitude and a posterior slow shifting towards the QRS-complex. Finally, several VRD indices have reached the steady state before the RR interval. This work provides the range of values for VRD in normal conditions during abrupt HR changes. Outside this range, we could suppose that it exists a cardiac risk.