Vectorcardiographic evaluation of ventricular repolarization in healthy individuals and LQTS mutation carriers

Ventricular arrhythmia is a well-known cause of syncopal attacks and sudden cardiac death in humans. Ventricular repolarization (VR) is the most unstable phase in cardiac electrical activity and its regulation depends on the coordinated activity in multiple ion channels. Several physiological factors such as heart rate (HR), autonomic nervous system (ANS) activity, gender and age influence the function of these ion channels. Meanwhile there are some genetic disorders e.g. the long QT syndrome (LQTS), which by changing (increase or decrease) the function of the ion channels can cause an imbalance in ion currents and subsequently increase the propensity for ventricular arrhythmias. Evaluation of VR in response to both physiological and pathophysiological factors is of great importance for understanding the mechanism of ventricular arrhythmias. Vectorcardiography (VCG) as a noninvasive tool in evaluation of global VR has proven superior to scalar ECG and, therefore, been used in this project.