Sinus bradycardia and sinus tachycardia may be normal or clinical depending on the underlying cause.

窦性心动过缓和窦性心动过速可能是正常现象或临床病变，具体取决于根本原因。

For example, sinus bradycardia is considered normal during sleep and sinus tachycardia may be normal during physical exercises.

例如，睡眠期间窦性心动过缓被认为是正常的，体育锻炼期间窦性心动过速可能是正常的。

Sinus tachycardia: when the SA node fires more than 100 times per minute generating a faster heart rate of greater than 100 beats per minute.

当SA结放电超过100次/分钟时，产生大于100次/分钟的更快心率。