Instability in action potential morphology underlies phase 2 reentry: a mathematical modeling study
A Maoz, T Krogh-Madsen, DJ Christini - Heart Rhythm, 2009 - Elsevier
A Maoz, T Krogh-Madsen, DJ Christini
Heart Rhythm, 2009•ElsevierBACKGROUND: Phase 2 reentry occurs when electrotonic current propagates from sites of
normal notch-and-dome action potentials (APs) to loss-of-dome abbreviated AP sites,
causing abnormal reexcitation. The existence of two neighboring regions exhibiting these
two different AP morphologies is believed to be sufficient for local reexcitation and
development of phase 2 reentry. OBJECTIVE: The purpose of this study was to investigate
the mechanism of phase 2 reentry development in simulated tissues having no gradient or …
normal notch-and-dome action potentials (APs) to loss-of-dome abbreviated AP sites,
causing abnormal reexcitation. The existence of two neighboring regions exhibiting these
two different AP morphologies is believed to be sufficient for local reexcitation and
development of phase 2 reentry. OBJECTIVE: The purpose of this study was to investigate
the mechanism of phase 2 reentry development in simulated tissues having no gradient or …
BACKGROUND
Phase 2 reentry occurs when electrotonic current propagates from sites of normal notch-and-dome action potentials (APs) to loss-of-dome abbreviated AP sites, causing abnormal reexcitation. The existence of two neighboring regions exhibiting these two different AP morphologies is believed to be sufficient for local reexcitation and development of phase 2 reentry.
OBJECTIVE
The purpose of this study was to investigate the mechanism of phase 2 reentry development in simulated tissues having no gradient or continuous gradients of ionic currents that affect phase 2. In particular, we investigated gradients of the transient outward current conductance Gto, representing hypothesized right ventricular Gto gradients.
METHODS
Single-cell simulations of Luo-Rudy dynamic model cells with a range of Gto values were performed. In addition, one-dimensional fiber simulations were used to investigate the spatiotemporal phenomenon of phase 2 reentry.
RESULTS
In single-cell simulations, low and normal values of Gto produced the notch-and-dome morphology, whereas high values of Gto produced abbreviated APs with loss-of-dome morphology. However, intermediate values of Gto caused cells to switch intermittently between the two morphologies during constant pacing. Phase 2 reentry occurred in homogeneous and heterogeneous cable simulations, but only when a mass of cells had Gto values close to the unstable “switching” behavior range.
CONCLUSION
A main factor underlying phase 2 reentry apparently is not the presence of two different stable morphologies in adjacent regions but rather unstable switching AP morphology within a significant subset of cells.
Elsevier