ECG 1: What is the criteria for Normal Sinus Rhythm (NSR) ?

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ECG 1: What is the criteria for Normal Sinus Rhythm (NSR) ?

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Normal sinus rhythm

asked May 22, 2013 in Medical Academics Questions by Mike Junior Resident (2,007 points)

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1 Answer

John Snow

2,007 points Approved user

In normal sinus rhythm (NSR), pacemaker impulses are initiated in SA node, travel through the atrial pathways, and are delayed at the AV node. Depolarization of the atria produces a P wave. Impulse conduction proceeds unimpeded through the AV node and down the bundle branches to Purkinje fibers in the ventricles, causing ventricular depolarization and normally producing a narrow QRS complex.

Criteria:

The P wave is usually upright in leads II, III, aVF and V1. Its morphology remains constant at all times.
P-P and R-R intervals are equal and regular.
Atrial and ventricular rates are identical and range between 60 and 100 bpm.
PR interval: Normal (0.12-0.2 seconds)
QRS: Normal (0.6-0.1 seconds)

Note: A normal ECG does not exclude heart disease.