Sinus Tachycardia - ECG
Sinus tachycardia is a very frequent finding. It is a normal sinus rhythm when QRS complexes are preceded by P waves but the heart rate is higher than 90 beats per minute.
This is a two-lead record of sinus tachycardia. The QRS complexes are preceded by P waves (red arrow). If the paper speed is normal, the distance between two QRS complexes is about 2.5 large squares and that corresponds to the heart rate of about 120 beats per minute
Conclusion: Sinus tachycardia is usually a secondary reaction to physical or psychical stress. We can diagnose it in cases of acute physical exertion, mental strain, fever, delirium states, etc.