Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue

Abstract

Waveblock formation is the main cause of reentry. We have performed a comprehensive numerical modeling study of block formation due to anisotropy in Ten Tusscher and Panfilov (2006) ionic model for human ventricular tissue. We have examined the border between different areas of myocardial fiber alignment and have shown that blockage can occur for a wave traveling from a transverse fiber area to a longitudinal one. Such blockage occurs for reasonable values of the anisotropy ratio (AR): from 2.4 to 6.2 with respect to propagation velocities. This critical AR decreases by the suppression of I Na and I Ca, slightly decreases by the suppression of I Kr and I Ks, and substantially increases by the suppression of I K1. Hyperkalemia affects the block formation in a complex, biphasic way. We provide examples of reentry formation due to the studied effects and have concluded that the suppression of I K1 should be the most effective way to prevent waveblock at the areas of abrupt change in anisotropy.

Overdrive pacing of spiral waves in a model of human ventricular tissue

“…We considered homogeneous cardiac tissue without anisotropy. Each of the factors of ionic heterogeneity 42 , 43 , non-conductive obstacles 44 , 45 , anisotropy 46 , 47 and 3D effects 48 can result in the onset of a new spiral wave under high-frequency pacing, which can interfere with the LVC process and make it more difficult.…”

Wave Propagation in Inhomogeneous Excitable Media

“…In cardiac muscle such a change in coupling can occur also due to tissue anisotropy and initiate a wave propagation block (112). Furthermore, numerical analysis shows that under certain conditions this block can result in formation of a re-entrant source of an excitation or vortex (113). This process is illustrated in Figure 16, where wave dynamics within a medium is demonstrated by two strips with orthogonal fiber orientation.…”

“…As a result of this drift, the vortex finally disappears at the upper medium boundary. The drift can be limited in the medium of a more complicated inhomogeneity, e.g., by adding an isotropic area near the upper medium boundary (113).…”

Initiation of Rotors by Fast Propagation Regions in Excitable Media: A Theoretical Study

“…An abrupt transition of the coupling gradient would block the wave propagation, but nearby parts with a smooth transition would not and therefore cause a reentry. The wave blockage was also found in a model of human ventricular tissue due to an abrupt transition of the anisotropic coupling [30].…”