A 76-year-old woman was seen in her family doctor's office for an ECG. The ECG showed atrial fibrillation with an irregular ventricular rhythm of 66 beats per minute and no P waves. The QRS axis, duration, and morphology were normal as were the ST segment and T waves. The final diagnosis was atrial fibrillation with a controlled ventricular rate of 66 beats per minute and no other abnormalities.

1. Stepwise interpretation of ECG
ID 383

2. ID 383 – 76 year old woman in her family doctor’s office

3. ID 383 – 76 year old woman in her family doctor’s office
Can you see P waves?

4. ID 383 – Atrial fibrillation with controlled ventricular rate (66/min)
There are no P waves. There are fibrillatory waves that vary in size and shape.
The ventricular rhythm is irregularly irregular (atrial fibrillation) – The rate is 66/min

5. ID 383 – Atrial fibrillation with controlled ventricular rate (66/min)
Let’s now look at the QRS complexes: There is normal QRS axis (between 0 and 90 degrees)

6. ID 383 – Atrial fibrillation with controlled ventricular rate (66/min)
The QRS duration is normal : There is no right bundle branch block, left bundle branch block
or non‐specific block

7. ID 383 – Atrial fibrillation with controlled ventricular rate (66/min)
There is no right ventricular hypertrophy or left ventricular hypertrophy

8. ID 383 – Atrial fibrillation with controlled ventricular rate (66/min)
There are no QRS signs of myocardial infarction –There are normal ST segment and normal T waves

9. ID 383
Final Diagnosis: Atrial fibrillation with controlled ventricular rate (66/min)
No other abnormalities
There are no QRS signs of myocardial infarction –There are normal ST segment and normal T waves

10. ID 383
Final Diagnosis: Atrial fibrillation with controlled ventricular rate (66/min)
No other abnormalities
There are no QRS signs of myocardial infarction –There are normal ST segment and normal T waves