2009 | OriginalPaper | Buchkapitel
Relationship between Maximal Upstroke Velocity of Transmembrane Voltage and Minimum Time Derivative of Extracellular Potential
verfasst von : Kwanghyun Sohn, Bonnie B. Punske, Frank B. Sachse
Erschienen in: Functional Imaging and Modeling of the Heart
Verlag: Springer Berlin Heidelberg
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The purpose of this computational study was to test the pertinence of the magnitude of the minimum time derivative of the extracellular potential, |dV
es
/dt
min
|, measured in a thin, conducting solution layer adjacent to the tissue, as an index of cardiac excitability. For this purpose, we performed computational studies characterizing the relationship between |dV
es
/dt
min
| and the maximum upstroke velocity of transmembrane voltage, dV
m
/dt
max
, which has been used in previous studies as an index of excitability. A three-dimensional bidomain model of electrical conduction in cardiac tissue was used based on the Noble-Varghese-Kohl-Noble model of ventricular myocytes. The spatial domain included a slab of cardiac tissue with intra- and extracellular anisotropic conductivities surrounded by a layer of solution. The simulations showed linear relationships between |dV
es
/dt
min
| and dV
m
/dt
max
for reduction of maximum sodium current conductance (G
Na
) from 100% to 20%. The relationship was dependent on location and propagation direction. However, when both parameters were normalized, those dependencies disappeared. In summary, our study demonstrated that normalized |dV
es
/dt
min
| is linearly related to normalized dV
m
/dt
max
. The results support our hypothesis that normalized |dV
es
/dt
min
| can be used as an index of cardiac excitability.