Mechanisms of the acute ischemia-induced arrhythmogenesis – A simulation study

Zhang, Hong; Zhang, Zhenxi; Yang, Lin; Jin, Yinbin; Huang, Yanna

doi:10.1016/j.mbs.2006.06.003

Cited by 7 publications

(14 citation statements)

References 22 publications

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“…During point stimulation, local superfusion of these three agents resulted in wave front concavities in the central zone where the drug was applied (Fig. 4), similar to the effect shown in modeling studies with an area of regional ischemia (7,12,28) or elevated K ϩ (1). These concavities reflect a local decrease in CV in the central zone compared with the outer zone (Fig.…”

Section: Discussionsupporting

confidence: 63%

“…Concavity at the tip allows a higher source-to-load ratio and faster local CV (11), which permits the wave front to maintain its rotational speed and carry on despite being in a region of depressed conduction. In the only report of which we are aware (28), an S-shaped wave front can be seen in a computational simulation in which a spiral wave partially invades an area of moderate ischemia to which it is anchored. In our experiments, the S-shape reverted to a purely convex shape upon washout and was quantified by area differences (Fig.…”

Section: Discussionmentioning

confidence: 98%

“…Heterogeneity has been studied methodically in computational models using regions with prolonged refractoriness (19), elevated extracellular K ϩ concentration (1,27), cell-cell decoupling (6), or simulated ischemia (7,12,28). Common among these situations is the localized slowing of conduction, which facilitates the formation of conduction block that is a prerequisite for reentry.…”

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confidence: 99%

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Region of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers

Lin¹,

Garber

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

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in cardiac tissue is related to the occurrence of arrhythmias. Of importance are regions of slowed conduction, which have been implicated in the formation of conduction block and reentry. Experimentally, it has been a challenge to produce local heterogeneity in a manner that is both reversible and well controlled. Consequently, we developed a dual-zone superfusion chamber that can dynamically create a small (5 mm) central island of heterogeneity in cultured cardiac cell monolayers. Three different conditions were studied to explore the effect of regionally slowed conduction on wave propagation and reentry: depolarization by elevated extracellular potassium, sodium channel inhibition with lidocaine, and cell-cell decoupling with palmitoleic acid. Using optical mapping of transmembrane voltage, we found that the central region of slowed conduction always served as the core region around which a spiral wave formed and then revolved following a period of rapid pacing. Because of the localized slowing in the core region, we observed experimentally for the first time an S shape of the spiral wave front near its tip. These results indicate that a small region of slowed conduction can play a crucial role in the formation, anchoring, and modulation of reentrant spiral waves.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 99%

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Region of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers

Lin¹,

Garber

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

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“…With this approach, the relative error can decline about 2%. Details of the solving procedures can be found in Zhang et al (2006).…”

Section: Numerical Solutionmentioning

confidence: 99%

“…Up to now most of the simulation researches have not yet taken transmural heterogeneity into consideration (Xie et al 2001;Clayton et al 2002;Blanca et al 2004;Zhang et al 2006;Trenor et al 2007). However, it has been demonstrated that there are regional differences in electrical activities in the ventricular wall of the guinea pig, canine, and human (Akar et al 2002;Henry et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Effects of electrical heterogeneity on transmural reentry during acute global ischemia

Hong¹,

Jin²,

Zhang³

et al. 2010

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Abstract. Ventricular arrhythmias are commonly observed in patients with ischemia. It is reported that the electrophysiological changes evoked by ischemia are greater in the epicardium than in the endocardium. To investigate the effects of this heterogeneity on transmural reentry, the computer simulation method is used. A two-dimensional model which can reproduce the endocardial, epicardial and middle cell types, approximate the ischemic characteristics and distribution of the ischemic severity is developed by setting different ratios of the maximum conductance of the rapid and slow inward rectifier potassium currents and considering the three major component conditions of acute ischemia at the ionic level. The results demonstrate that action potentials of the ischemic cells have elevated resting potential, shortened duration, slowed upstroke and declined amplitude. Conduction velocity is much more depressed in the epicardium because of the ischemia-induced transmural gradient of excitability. The epicardially initiated activation has wider vulnerable window and more possibility to cause unidirectional propagation even reentry. Dispersion of the excitability is proposed to be the underlying mechanism.

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Study for relevance of the acute myocardial ischemia to arrhythmia by the optical mapping method

et al. 2007

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Ventricular arrhythmias are commonly observed in patients with acute coronary occlusion and ischemia. The purpose of the present study is to determine ischemic electrophysiological effects and their role in ischemia-induced arrhythmia. Optical mapping of the membrane potential with voltage-sensitive dyes was used in the study. The mapping was performed with di-4-ANEPPS in Langendorff-perfused rabbit hearts. The excitation-contraction decoupler 2,3-butanedione monoxime was used to suppress motion artifacts caused by contraction of the heart. The acute global ischemia was developed by a rapid reduction of the flow rate. The experiments revealed that ischemic tissues were characterized by an obvious reduction in action potential duration and action potential upstroke, slower conduction velocity (CV) and the property of post-repolarization refractoriness. Moreover, the magnitude of CV reduced both in control and ischemia when the pacing cycle length was short. CV reduction was even early in ischemia, resulting in a broader curve during ischemia. Moreover, the dominant frequency of ventricular tachycardia/ventricular fibrillation (VT/VF) in ischemia was less than that in control, implying a decreasing tendency of VT/VF frequency for low excitability. Therefore, combined with our previous simulation study, the dynamic changes of CV and longer refractory period were suggested to play an important role in the ischemia-related arrhythmia. Low excitability in ischemic tissue was the fundamental mechanism in it.

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Mechanisms of the acute ischemia-induced arrhythmogenesis – A simulation study

Cited by 7 publications

References 22 publications

Region of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers

Region of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers

Effects of electrical heterogeneity on transmural reentry during acute global ischemia

Study for relevance of the acute myocardial ischemia to arrhythmia by the optical mapping method

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