Fatigue occurs when the interval of intermittent tetanic contraction of skeletal muscle is shortened to a certain degree and the contractile tension declines.

骨骼肌间断强直收缩期间，当刺激间隔缩短到一定程度时，收缩张力呈现逐步降低，即产生疲劳现象。

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Results: Electromechanical delay time was longer in left atrium. Atrial contraction time and PR interval were longer in right side.

结果：左心房的电-机械延迟时间较长，右侧的心房收缩时间和心室的电-机械延迟时间较长。

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The study was focused on heart rate(HR) variation of sinus rhythm before 5 minutes attacking, relationship between premature atrial contraction, coupling interval and PAF episodes.

研究PAF发作与窦性心室率、前5分钟窦性心律的心率变异、房性期前收缩及其配对间期的关系。

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