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。
2
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。
3
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.