Computational simulations using the anisotropic bidomain model showed that hybrid monophasic action potential (HMAP) and electrogram markers are highly correlated with transmembrane action potentials.
Does the downstroke phase of hybrid monophasic action potentials reliably estimate cardiac repolarization times compared to transmembrane action potentials in a bidomain model?
Computational bidomain modeling demonstrates that the downstroke phase of hybrid monophasic action potentials provides reliable estimates of local cardiac repolarization times.
Unipolar electrograms (EGs) and hybrid (or unorthodox or unipolar) monophasic action potentials (HMAPs) are currently the only proposed extracellular electrical recording techniques for obtaining cardiac recovery maps with high spatial resolution in exposed and isolated hearts. Estimates of the repolarization times from the HMAP downstroke phase have been the subject of recent controversies. The goal of this paper is to computationally address the controversies concerning the HMAP information content, in particular the reliability of estimating the repolarization time from the HMAP downstroke phase. Three-dimensional numerical simulations were performed by using the anisotropic bidomain model with a region of short action potential durations. EGs, transmembrane action potentials (TAPs), and HMAPs elicited by an epicardial stimulation close or away from a permanently depolarized site were computed. The repolarization time was computed as the moment of EG fastest upstroke (RT(eg)) during the T wave, of HMAP fastest downstroke (RT(HMAP)), and of TAP fastest downstroke (RT(tap)). The latter was taken as the gold standard for repolarization time. We also compared the times (RT90(HMAP), RT90(tap)) when the HMAP and TAP first reach 90% of their resting value during the downstroke. For all explored sites, the HMAP downstroke closely followed the TAP downstroke, which is the expression of local repolarization activity. Results show that HMAP and TAP markers are highly correlated, and both markers RT(HMAP) and RT(eg) (RT90(HMAP)) are reliable estimates of the TAP reference marker RT(tap) (RT90(tap)). Therefore, the downstroke phase of the HMAP contains valuable information for assessing repolarization times.
Franzone et al. (Sat,) conducted a other in Cardiac repolarization times. Hybrid monophasic action potentials (HMAPs) and unipolar electrograms (EGs) vs. Transmembrane action potentials (TAPs) was evaluated on Repolarization time estimates (RT(HMAP), RT(eg), RT90(HMAP)) compared to gold standard (RT(tap), RT90(tap)). Computational simulations using the anisotropic bidomain model showed that hybrid monophasic action potential (HMAP) and electrogram markers are highly correlated with transmembrane action potentials.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: