Dynamic origin of spatially discordant alternans in cardiac tissue
Dynamic origin of spatially discordant alternans in cardiac tissue
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DOI：
10.1529/biophysj.106.091009
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发表时间：
2007-01-01
影响因子：
3.4
通讯作者：
Qu, Zhilin
中科院分区：
文献类型：
--
作者：
Hayashi, Hideki;Shiferaw, Yohannes;Qu, Zhilin
周期性刺激的心脏细胞的机电反应出现搏动交替，这种情况与危及生命的室性心律失常的发生有关。动物心脏表面膜电压（V-m）和细胞内钙（Ca-i）的光学成像揭示了复杂的交替空间模式。特别是，在大-小-大动作电位持续时间（APD）区域与小-大-小动作电位持续时间（APD）区域相邻的非相位交替中，观察到空间不协调交替。然而，导致不协调交替发生和控制其时空特性的潜在机制尚不清楚。通过数学建模，我们发现不协调交替的空间分布的动态变化可以用来确定潜在的机制。节律兔心脏V-m和Ca-i的光学映射揭示了快速起搏引起的空间不协调交替表现出与理论研究一致的纯动力学机制。我们的研究结果支持这样一种观点，即心脏的空间不协调交替可以通过不需要组织异质性的动态模式形成过程形成。
Alternans, a condition in which there is a beat-to-beat alternation in the electromechanical response of a periodically stimulated cardiac cell, has been linked to the genesis of life-threatening ventricular arrhythmias. Optical mapping of membrane voltage (V-m) and intracellular calcium (Ca-i) on the surface of animal hearts reveals complex spatial patterns of alternans. In particular, spatially discordant alternans has been observed in which regions with a large-small-large action potential duration (APD) alternate out-of-phase adjacent to regions of small-large-small APD. However, the underlying mechanisms that lead to the initiation of discordant alternans and govern its spatiotemporal properties are not well understood. Using mathematical modeling, we show that dynamic changes in the spatial distribution of discordant alternans can be used to pinpoint the underlying mechanisms. Optical mapping of V-m and Ca-i in paced rabbit hearts revealed that spatially discordant alternans induced by rapid pacing exhibits properties consistent with a purely dynamical mechanism as shown in theoretical studies. Our results support the viewpoint that spatially discordant alternans in the heart can be formed via a dynamical pattern formation process which does not require tissue heterogeneity.