Characteristics of normal sinus rhythm

Normal sinus rhythm (NSR) is the characteristic rhythm of the healthy human heart (Uptodate.com 2013) NSR is considered to be present if the heart rate is in the normal range, the P waves are normal on the ECG, and the rate does not vary significantly. If, however, the R-R interval is variable, the rhythm is called sinus arrhythmia. A sinus rhythm faster than the normal range is called a sinus tachycardia while a slower rate is called a sinus Bradycardia. The normal heart rate has been considered to be between 60 and 100 beats/min.