3 Normal Sinus Rhythm

A cardiac rhythm strip only indicates normal sinus rhythm (NSR) when all of the following criteria are fulfilled:

1. The rhythm is regular with consistent R-R intervals
2. Atrial and ventricular rates between 60 – 100 beats per minute (bpm)
3. Each QRS complex is preceded by a distinct P wave
4. The PR interval remains constant and within the normal range (0.12 – 0.20 secs)
5. The QRS complex width is narrow (<0.12 secs)
6. A palpable pulse and measurable blood pressure are present

When these conditions are met in the rhythm strip, it suggests a normal sinus origin (i.e., SA node) and the typical conduction of the cardiac electrical impulse is associated with NSR. Figure 3.1 below provides an example of NSR on a 6-second rhythm strip.

Figure 3.1  Normal sinus rhythm.^[1]