Abstract The V-index is a recently-proposed metric related to repolarization heterogeneity (RH) Introduction Spatial heterogeneity of ventricular repolarization is a key quantity for the development of arrhythmias. Despite many methods have been proposed and investigated in the past [1-3], a non-invasive quantification of Repolarization Heterogeneity (RH) is still an open issue We recently proposed an estimator of the standard deviation of RH, which was named "V-index" Although the performances of the method have been deeply investigated in the original paper Method An estimate of repolarization heterogeneity Let us suppose to subdivide the myocardium in "nodes", each node m sharing a common transmembrane potential (TMP), D(t), but having a specific repolarization time given by ρ m =ρ + Δρ m . At each node m, the repolarization delay Δρ m is the deviation from the average repolarization timeρ = 1 M M m=1 ρ m in the given heartbeat. We have recently [5] introduced a simple model to describe the distribution of these delays Δρ m (k) among beats, being k the beat index. In particular we set: where ϑ m models the spatial variability of the repolarization times for a given subject at a given HR, and ϕ m (k) describes difference in repolarization times which are observable among successive beats
