2. Originate at the Sinus Node Normal Sinus Rhythm (NSR) Sinus Bradycardia Sinus Tachycardia Sinus Arrhythmia

3. NSR Technically, it is not an arrhythmia because it is a normal, rhythmic pattern. Arrhythmia, dysrhythmia, or rhythm all used interchangeably

4. Since the SA node inherently fires at a rate of 60-100bpm… If the EKG rhythm is slower or faster, it is not considered a normal sinus rhythm.

5. If ANY measurements fall outside of the normal limits… It is not a NSR.

6. Rules for NSR Rate: 60-100 bpm P wave: uniform shape: one P wave in front of every QRS complex PRI:.12-.20 seconds and constant QRS: less than.12 seconds

7. Sinus Bradycardia When a rhythm originates in the sinus node, but the rate is slower than 60 bpm.

8. Rules for Sinus Bradycardia Regularity: regular Rate: The atrial and ventricular rates are equal;heart rate is less than 60 bpm P wave: there is a uniform P wave in front of every QRS complex. PRI: The PR interval measures between.12 and.20 seconds; the PRI measurement is constant across the strip. QRS: The QRS complex measures less than.12 seconds.

9. Sinus Tachycardia When the rate is more than 100 bpm. Rules are the same, except rate is usually between 100- 160 bpm.

10. Sinus Arrhythmia The rate changes with the patient’s respirations. When breathing in, the rate increases; when breathing out, the rate decreases. Causes an irregular R-R interval.