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。

The most common variations of sinus rhythm include: - Sinus bradycardia: when the SA node fires less than 60 times per minute resulting in a slower heart rate of less than 60 beats per minute.

心率为60-100次/分钟。窦性心律最常见的变体包括：-窦性心动过缓：当SA结放电少于60次/分钟，导致心率低于60次/分钟。