Published online Sep 26, 2020. doi: 10.4330/wjc.v12.i9.437
Peer-review started: February 28, 2020
First decision: May 28, 2020
Revised: June 11, 2020
Accepted: August 24, 2020
Article in press: August 24, 2020
Published online: September 26, 2020
Repolarization heterogeneity (RH) is an intrinsic property of ventricular myocardium and the reason for T-wave formation on electrocardiogram (ECG). Exceeding the physiologically based RH level is associated with appearance of life-threatening ventricular arrhythmias and sudden cardiac death. In this regard, an accurate and comprehensive evaluation of the degree of RH parameters is of importance for assessment of heart state and arrhythmic risk. This review is devoted to comprehensive consideration of RH phenomena in terms of electrophysiological processes underlying RH, cardiac electric field formation during ventricular repolarization, as well as clinical significance of RH and its reflection on ECG parameters. The formation of transmural, apicobasal, left-to-right and anterior-posterior gradients of action potential durations and end of repolarization times resulting from the heterogenous distribution of repolarizing ion currents and action potential morphology throughout the heart ventricles, and the different sensitivity of myocardial cells in different ventricular regions to the action of pharmacological agents, temperature, frequency of stimulation, etc., are being discussed. The review is focused on the fact that RH has different aspects – temporal and spatial, global and local; ECG reflection of various RH aspects and their clinical significance are being discussed. Strategies for comprehensive assessment of ventricular RH using different ECG indices reflecting various RH aspects are presented.
Core Tip: A comprehensive assessment of ventricular repolarization process is an important part of electrocardiogram (ECG) diagnostics. First of all, the increased repolarization heterogeneity is associated with arrhythmogenesis. Besides, repolarization disturbances reflect the degree of electric remodeling of myocardium related to heart failure degree and mortality. We herein discuss the electrophysiological basis for repolarization heterogeneity and the factors that modulate it. We demonstrate that repolarization heterogeneity has various aspects – temporal and spatial, global and local, and there is a need in different ECG-indices to evaluate all the aspects.