Evaluating body surface ECG differences of simulated long-QT syndromes

Congenital Long-QT Syndrome (LQTS) is a genetic disorder affecting the repolarization of the heart. The most prevalent subtypes of LQTS are LQT1-3. In this work, we aim to evaluate the differences in the T-waves of simulated LQT1-3 in order to identify markers in the ECG that might help to classify patients solely based on ECG measurements. For LQT1, mutation S277L was used to characterize I
Ks
and mutation S818L in I
Kr
for LQT2. Voltage clamp data were used to parametrize the ion channel equations of the ten Tusscher and Panfilov model of human ventricular electrophysiology. LQT3 was integrated using an existing mutant INa model. The monodomain model was used in a transmural and apico-basal heterogeneous model of the ventricles to calculate ventricular excitation propagation. The forward calculation on a torso model was performed to determine body surface ECGs. Compared to the physiological case with a QT-time of 375 ms, this interval was prolonged in all LQTS (LQT1 423 ms; LQT2 394 ms; LQT3 405 ms). The T-wave amplitude was changed (Einthoven lead II: LQT1 108%; LQT2 91%; LQT3 103%). Also, the width of the T-wave was enlarged (full width at half maximum: LQT1 111%; LQT2 125%; LQT3 109%). At the current state of modeling and data analysis, the three LQTS have not been distinguishable solely by ECG data.