QT Intervals Are Prolonging Simultaneously with Increasing Heart Rate during Dynamical Experiment in Healthy Horses

Abstract

Prolonging of QT intervals was published numerously and it is considered as a significant factor in prediction of sudden death. Available sources are occupied by analysis of static re-cords, i.e. without transient processes. We have recorded ECG data in horses that show clear prolonging of QT intervals during increasing heart rate in dynamical experiment. Generally speaking it is suggested as great risk of sudden heart failure. Paradoxically those records were measured in well trained horses. We suppose that such a phenomenon is caused by changes in nervous control of a heart. We have developed several model structures of QT intervals control. Simulation results indicate that generally accepted attitude to QT intervals control is misguiding or incomplete. We have proved theoretically that the abnormalities are caused by variant sensitivity of ventricular cells to sympathetic and parasympathetic during repolarisation phase.