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Impaired Sarcoplasmic Reticulum Calcium Uptake and Release Promote Electromechanically and Spatially Discordant Alternans: A Computational Study.

Weinberg SH - Clin Med Insights Cardiol (2016)

Bottom Line: Cardiac electrical dynamics are governed by cellular-level properties, such as action potential duration (APD) restitution and intracellular calcium (Ca) handling, and tissue-level properties, including conduction velocity restitution and cell-cell coupling.Irregular dynamics at the cellular level can lead to instabilities in cardiac tissue, including alternans, a beat-to-beat alternation in the action potential and/or the intracellular Ca transient.We find that an intermediate SR Ca uptake rate and larger SR Ca release resulted in the widest range of stimulus periods that promoted alternans.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA.

ABSTRACT
Cardiac electrical dynamics are governed by cellular-level properties, such as action potential duration (APD) restitution and intracellular calcium (Ca) handling, and tissue-level properties, including conduction velocity restitution and cell-cell coupling. Irregular dynamics at the cellular level can lead to instabilities in cardiac tissue, including alternans, a beat-to-beat alternation in the action potential and/or the intracellular Ca transient. In this study, we incorporate a detailed single cell coupled map model of Ca cycling and bidirectional APD-Ca coupling into a spatially extended tissue model to investigate the influence of sarcoplasmic reticulum (SR) Ca uptake and release properties on alternans and conduction block. We find that an intermediate SR Ca uptake rate and larger SR Ca release resulted in the widest range of stimulus periods that promoted alternans. However, both reduced SR Ca uptake and release promote arrhythmogenic spatially and electromechanically discordant alternans, suggesting a complex interaction between SR Ca handling and alternans characteristics at the cellular and tissue level.

No MeSH data available.


Related in: MedlinePlus

Reduced SR Ca uptake promotes complex spatial and electromechanical alternans patterns. APD and peak intracellular Ca are shown as a function of spatial location on even (black) and odd (red) beats, for SR Ca uptake rate v = (A) 0.7, (B) 0.4, (C) 0.35, and (D) 0.3. Other parameters: λ = 1, T = 288 ms.
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f5-cmc-suppl.1-2016-001: Reduced SR Ca uptake promotes complex spatial and electromechanical alternans patterns. APD and peak intracellular Ca are shown as a function of spatial location on even (black) and odd (red) beats, for SR Ca uptake rate v = (A) 0.7, (B) 0.4, (C) 0.35, and (D) 0.3. Other parameters: λ = 1, T = 288 ms.

Mentions: In Figure 5, we plot APD and peak intracellular Ca as a function of spatial location on even (black) and odd (red) beats, for T = 288 ms, varying SR Ca uptake rate ν. For ν = 0.7, APD and peak Ca are SD, with a node approximately at x = 5 cm, while at essentially all spatial locations, APD and peak Ca are EMC (Fig. 5A). For smaller ν = 0.4, alternans become SC (Fig. 5B), and then transition to SD again for ν = 0.35 (Fig. 5C). For ν = 0.3, alternans remain SD but become EMD as well (Fig. 5D).


Impaired Sarcoplasmic Reticulum Calcium Uptake and Release Promote Electromechanically and Spatially Discordant Alternans: A Computational Study.

Weinberg SH - Clin Med Insights Cardiol (2016)

Reduced SR Ca uptake promotes complex spatial and electromechanical alternans patterns. APD and peak intracellular Ca are shown as a function of spatial location on even (black) and odd (red) beats, for SR Ca uptake rate v = (A) 0.7, (B) 0.4, (C) 0.35, and (D) 0.3. Other parameters: λ = 1, T = 288 ms.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4920205&req=5

f5-cmc-suppl.1-2016-001: Reduced SR Ca uptake promotes complex spatial and electromechanical alternans patterns. APD and peak intracellular Ca are shown as a function of spatial location on even (black) and odd (red) beats, for SR Ca uptake rate v = (A) 0.7, (B) 0.4, (C) 0.35, and (D) 0.3. Other parameters: λ = 1, T = 288 ms.
Mentions: In Figure 5, we plot APD and peak intracellular Ca as a function of spatial location on even (black) and odd (red) beats, for T = 288 ms, varying SR Ca uptake rate ν. For ν = 0.7, APD and peak Ca are SD, with a node approximately at x = 5 cm, while at essentially all spatial locations, APD and peak Ca are EMC (Fig. 5A). For smaller ν = 0.4, alternans become SC (Fig. 5B), and then transition to SD again for ν = 0.35 (Fig. 5C). For ν = 0.3, alternans remain SD but become EMD as well (Fig. 5D).

Bottom Line: Cardiac electrical dynamics are governed by cellular-level properties, such as action potential duration (APD) restitution and intracellular calcium (Ca) handling, and tissue-level properties, including conduction velocity restitution and cell-cell coupling.Irregular dynamics at the cellular level can lead to instabilities in cardiac tissue, including alternans, a beat-to-beat alternation in the action potential and/or the intracellular Ca transient.We find that an intermediate SR Ca uptake rate and larger SR Ca release resulted in the widest range of stimulus periods that promoted alternans.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, USA.

ABSTRACT
Cardiac electrical dynamics are governed by cellular-level properties, such as action potential duration (APD) restitution and intracellular calcium (Ca) handling, and tissue-level properties, including conduction velocity restitution and cell-cell coupling. Irregular dynamics at the cellular level can lead to instabilities in cardiac tissue, including alternans, a beat-to-beat alternation in the action potential and/or the intracellular Ca transient. In this study, we incorporate a detailed single cell coupled map model of Ca cycling and bidirectional APD-Ca coupling into a spatially extended tissue model to investigate the influence of sarcoplasmic reticulum (SR) Ca uptake and release properties on alternans and conduction block. We find that an intermediate SR Ca uptake rate and larger SR Ca release resulted in the widest range of stimulus periods that promoted alternans. However, both reduced SR Ca uptake and release promote arrhythmogenic spatially and electromechanically discordant alternans, suggesting a complex interaction between SR Ca handling and alternans characteristics at the cellular and tissue level.

No MeSH data available.


Related in: MedlinePlus