A 50-year-old man presented with palpitations. An ECG showed atrial flutter with a ventricular rate of 107 beats per minute and variable atrioventricular block. The QRS complex was normal in axis and duration with no signs of ventricular hypertrophy or prior myocardial infarction. Due to the saw-tooth pattern of atrial flutter waves, the T waves were difficult to assess in the inferior leads and V6.

1. Stepwise interpretation of ECG
ID 122
Atrial flutter

2. ID 122 – 50 year old man complaining of palpitation

3. ID 122 – 50 year old man complaining of palpitation
Can you see P waves?

4. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
We can see typical waves of atrial flutter with variable AV block – ventricular rate = 107/min.

5. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
Let’s now look at the QRS complex. It is positive in I and slightly positive or isoelectric in aVF –
The QRS axis is normal.

6. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
The QRS duration is normal – There are no signs of right or left bundle branch block
or nonspecific block

7. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
There no signs of right or left ventricular hypertrophy

8. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
The QRS shows no signs of myocardial infarction

9. ID 122 – Atrial flutter with variable AV block – Ventricular rate 107/min.
Because of the saw-like waves of atrial flutter, it is difficult to assess the T waves in the
inferior leads and V6. In the other leads the T waves are normal.

10. ID 122 - Final diagnosis - Atrial flutter with variable AV block – Ventricular rate 107/min.
Because of the saw-toothed waves of atrial flutter, it is difficult to assess the T waves in the
inferior leads and V6. In the other leads the T waves are normal.