The Patient: This excellent teaching case was donated to the ECG Guru by our friend, Sebastian Garay (who is an ECG Guru himself). It was taken from a 33-year-old man who was complaining of chest pain and palpitations. He reported a similar episode about six months prior, but failed to follow up with cardiology. Was told by his medical care provider that he had atrial fib.
The ECG: We are able in this case to provide a 12-lead ECG with each lead recorded for the entire width of the paper. This has the advantage of producing twelve ten-second rhythm strips. Page one contains the limb leads, and page two shows us the precordial leads.
The rhythm is atrial fibrillation, with a heart rate of 133 bpm and an irregularly irregular rhythm. The QRS axis is extreme left at about -75 degrees. This has caused Leads II, III, and aVF to be negatively deflected, and aVR and aVL to be positive. Lead I is biphasic, low voltage, and mostly positive, indicating that the axis travels almost perpendicular to Lead I, but slightly toward it.
The machine mistakenly gives us a reading for PR interval and P wave axis, even though there are no P waves. The QRS is on the wide side without being abnormal at .10 seconds (100 ms). The QTc is within normal limits, although it might be considered “borderline”, with 431-450 usually considered borderline.