This ECG was obtained from a 24-year-old man who was seen in the Emergency Department for chest pain that was determined to be non-cardiac in origin.  He had a fever and cough, with pain on inspiration. His vital signs were within normal range, and he appeared well-perfused. There was no complaint of dizziness or syncope.

So, what does his ECG show?  The ECG should be interpreted in the context of the age and presentation of the patient.  He is young, and has been healthy all his life.  He is lean and reasonably fit.

The rhythm:  the rate is 81 bpm, and the rhythm is regular.  His P waves are upright in Leads I and II, and they are followed by QRS complexes.  The rhythm is NORMAL SINUS RHYTHM.

Intervals:  The PR interval is 137 ms (.137 seconds), and his QRS duration is 91 ms (0.9 seconds).  His QTc is 404 ms.  All are within normal range.

QRS frontal plane axis:  Normal axis, at around 30 degrees.  Lead II has the tallest QRS of the limb leads, which is an indication of axis in the normal range.  When the electrical axis travels towards Lead II, we can expect Lead aVL to be small, or even biphasic.