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This Article Full Text Full Text (PDF) All Versions of this Article: 293/5/H2771    most recent 00651.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Colli Franzone, P. Articles by Taccardi, B. Search for Related Content PubMed PubMed Citation Articles by Colli Franzone, P. Articles by Taccardi, B.

Monophasic action potentials generated by bidomain modeling as a tool for detecting cardiac repolarization times

¹Dipartimento di Matematica, Università degli Studi di Pavia, Pavia, Italy; ²Dipartimento di Matematica, Università degli Studi di Milano, Milan, Italy; and ³Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah

Submitted 6 June 2007 ; accepted in final form 16 August 2007

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.

unipolar electrograms; monophasic action potential; bidomain model; heterogeneity; action potential duration