Transmural Ventricular Heterogeneities Play a Major Role in Determining T-Wave Morphology at Different Serum Potassium Levels

Syed Hassaan Ahmed Bukhari1, Flavio Palmieri2, Dina Ferreira3, Mark Potse4, Julia Ramırez5, Pablo Laguna6, Carlos Sanchez7, Esther Pueyo1
1University of Zaragoza, 2Centre de Recerca en Enginyeria Biom`edica, Universitat Polit`ecnica de Catalunya, Barcelona, Spain, 3Laboratorios Rubio,, 4Inria Bordeaux Sud-Ouest, 5William Harvey Research Institute, Queen Mary University of London, London, United Kingdom, 6Zaragoza University, 7Defence University Centre (CUD), General Military Academy of Zaragoza (AGM), Zaragoza, Spain


Background and aim: End-stage renal disease (ESRD) affects more than 10% of the population. ESRD patients present impaired potassium homeostasis, which increases the risk for ventricular arrhythmias and sudden cardiac death. Preventive, noninvasive estimation of serum potassium, [K+], is therefore of major importance. We investigated three T-wave morphological descriptors, assessed their relationship with [K+], and ascertained mechanisms responsible for their large inter-individual differences. Methods: Electrocardiograms (ECGs) of twelve ESRD patients undergoing hemodialysis and ECGs calculated from simulated ventricular fibers were processed to quantify the T-wave width (Tw), slope-to-amplitude ratio (TSA) and temporal morphological variability (dw). [K+] was measured at different time points during hemodialysis and simulated from 2 to 8 mmol/l in the modeled ventricular fibers. Results: In ESRD patients, Tw, TSA and dw were closely related with [K+] during hemodialysis, with median Spearman correlation coefficients of -0:5, 0.8 and 0.65, respectively. However, the pattern of such relationships depended highly on the characteristics of each patient. This variability, more manifest at high [K+], was reproduced in the simulations. Simulated descriptors were highly sensitive to the proportion of mid-myocardial cells, with 10% variations in this proportion leading to more than 15% changes in the T-wave descriptors. Conclusions: Changes in [K+] have remarkable effects on Tw, TSA and dw, but the pattern of the relationship is highly patient-dependent, particularly under elevated [K+]. Differences in the proportion of mid-myocardial cells may play a role in explaining such inter-individual variability.