Abstract
Background - Spatially discordant alternans (SDA) has been linked to life-threatening arrhythmias. The mechanisms underlying SDA development in cardiac tissue remain unclear. Methods and results - We investigated the role of conduction velocity (CV) restitution and short-term memory in the organization and evolution of alternans in action potential duration using high-resolution optical mapping of the epicardial surface in 8 isolated, Langendorff-perfused rabbit hearts. To assess the spatial organization of alternans, we tracked the evolution of nodal lines that separate out-of-phase regions of SDA. We measured the action potential duration heterogeneity index and maximal slope of CV restitution and estimated the effects of short-term memory by calculating time constant of action potential duration accommodation (τ). We found that 2 mechanisms underlie the development of SDA in the heart, leading to 2 distinct behaviors of nodal lines. The first mechanism is based on steep CV restitution and is associated with small τ and stable nodal lines. The second mechanism is associated with short-term memory (large τ) and is characterized by shallow CV restitution and unstable behavior of nodal lines. The maximum slope of the CV restitution was steeper (18.16±3.34 m/s) and τ was smaller (τ=4.31±0.33 stimuli) for areas with stable nodal lines than for areas with unstable nodal lines (6.32±0.96 m/s and τ=10.3±1.84 stimuli; P<0.01). Conlusions - Our results provide new insight into the mechanisms underlying SDA formation in the rabbit heart. Specifically, our results suggest that a new mechanism associated with short-term memory underlies SDA formation in the heart, in addition to steep CV restitution.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 17-25 |
| Number of pages | 9 |
| Journal | Circulation |
| Volume | 118 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jul 1 2008 |
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Keywords
- Action potentials
- Alternans
- Mapping
- Memory
- Restitution
Cite this
Role of conduction velocity restitution and short-term memory in the development of action potential duration alternans in isolated rabbit hearts. / Mironov, Sergey; Jalife, José; Tolkacheva, Elena G.
In: Circulation, Vol. 118, No. 1, 01.07.2008, p. 17-25.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Role of conduction velocity restitution and short-term memory in the development of action potential duration alternans in isolated rabbit hearts
AU - Mironov, Sergey
AU - Jalife, José
AU - Tolkacheva, Elena G.
PY - 2008/7/1
Y1 - 2008/7/1
N2 - Background - Spatially discordant alternans (SDA) has been linked to life-threatening arrhythmias. The mechanisms underlying SDA development in cardiac tissue remain unclear. Methods and results - We investigated the role of conduction velocity (CV) restitution and short-term memory in the organization and evolution of alternans in action potential duration using high-resolution optical mapping of the epicardial surface in 8 isolated, Langendorff-perfused rabbit hearts. To assess the spatial organization of alternans, we tracked the evolution of nodal lines that separate out-of-phase regions of SDA. We measured the action potential duration heterogeneity index and maximal slope of CV restitution and estimated the effects of short-term memory by calculating time constant of action potential duration accommodation (τ). We found that 2 mechanisms underlie the development of SDA in the heart, leading to 2 distinct behaviors of nodal lines. The first mechanism is based on steep CV restitution and is associated with small τ and stable nodal lines. The second mechanism is associated with short-term memory (large τ) and is characterized by shallow CV restitution and unstable behavior of nodal lines. The maximum slope of the CV restitution was steeper (18.16±3.34 m/s) and τ was smaller (τ=4.31±0.33 stimuli) for areas with stable nodal lines than for areas with unstable nodal lines (6.32±0.96 m/s and τ=10.3±1.84 stimuli; P<0.01). Conlusions - Our results provide new insight into the mechanisms underlying SDA formation in the rabbit heart. Specifically, our results suggest that a new mechanism associated with short-term memory underlies SDA formation in the heart, in addition to steep CV restitution.
AB - Background - Spatially discordant alternans (SDA) has been linked to life-threatening arrhythmias. The mechanisms underlying SDA development in cardiac tissue remain unclear. Methods and results - We investigated the role of conduction velocity (CV) restitution and short-term memory in the organization and evolution of alternans in action potential duration using high-resolution optical mapping of the epicardial surface in 8 isolated, Langendorff-perfused rabbit hearts. To assess the spatial organization of alternans, we tracked the evolution of nodal lines that separate out-of-phase regions of SDA. We measured the action potential duration heterogeneity index and maximal slope of CV restitution and estimated the effects of short-term memory by calculating time constant of action potential duration accommodation (τ). We found that 2 mechanisms underlie the development of SDA in the heart, leading to 2 distinct behaviors of nodal lines. The first mechanism is based on steep CV restitution and is associated with small τ and stable nodal lines. The second mechanism is associated with short-term memory (large τ) and is characterized by shallow CV restitution and unstable behavior of nodal lines. The maximum slope of the CV restitution was steeper (18.16±3.34 m/s) and τ was smaller (τ=4.31±0.33 stimuli) for areas with stable nodal lines than for areas with unstable nodal lines (6.32±0.96 m/s and τ=10.3±1.84 stimuli; P<0.01). Conlusions - Our results provide new insight into the mechanisms underlying SDA formation in the rabbit heart. Specifically, our results suggest that a new mechanism associated with short-term memory underlies SDA formation in the heart, in addition to steep CV restitution.
KW - Action potentials
KW - Alternans
KW - Mapping
KW - Memory
KW - Restitution
UR - http://www.scopus.com/inward/record.url?scp=50949125762&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=50949125762&partnerID=8YFLogxK
U2 - 10.1161/CIRCULATIONAHA.107.737254
DO - 10.1161/CIRCULATIONAHA.107.737254
M3 - Article
C2 - 18559701
AN - SCOPUS:50949125762
VL - 118
SP - 17
EP - 25
JO - Circulation
JF - Circulation
SN - 0009-7322
IS - 1
ER -