Studying the Basic ECG

INTRODUCTION

Normal sinus rhythm (NSR) is the characteristic rhythm of the healthy human heart. 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 (see “Sinus tachycardia”), while a slower rate is called a sinus bradycardia (see “Sinus bradycardia”).