EMS Registry ReadyExample 1 · lead II · 6 seconds
- Rate
- 68/min6 QRS complexes in 6 seconds × 10 = 60/min
- Rhythm
- Regular
- P waves
- Flutter waves (sawtooth), negative in II
- P to QRS
- 4:1, 4 flutter waves to each QRS
- PR
- None to measure
- QRS
- 0.08 s, narrow
Atrial flutter on an ECG strip
Sawtooth waves at about 300/min, with a QRS after every 2nd, 3rd or 4th wave.
What to look for
This is typical (counterclockwise) flutter. Sawtooth flutter waves run continuously at about 300/min, inverted in II, III and aVF, with no flat baseline between them. With a fixed ratio, the ventricular rate is regular: about 150 at 2:1, about 100 at 3:1 and about 75 at 4:1.
Examples
Each strip is 6 seconds of lead II, drawn to scale (25 mm a second, 10 mm a millivolt), so you can count boxes the way you would on paper. Each one is a different example, measured below it.
Example 2 · lead II · 6 seconds
- Rate
- 85/min8 QRS complexes in 6 seconds × 10 = 80/min
- Rhythm
- Regular
- P waves
- Flutter waves (sawtooth), negative in II
- P to QRS
- 3:1, 3 flutter waves to each QRS
- PR
- None to measure
- QRS
- 0.11 s, narrow
Example 3 · lead II · 6 seconds
- Rate
- 105/min11 QRS complexes in 6 seconds × 10 = 110/min
- Rhythm
- Regular
- P waves
- Flutter waves (sawtooth), negative in II
- P to QRS
- 3:1, 3 flutter waves to each QRS
- PR
- None to measure
- QRS
- 0.10 s, narrow
Don't confuse it with
- Atrial fibrillation
Irregularly irregular, with no P waves: only a fibrillating baseline.
- Supraventricular tachycardia (AVNRT)
Regular, narrow and 150-250/min, with no visible P waves.
- Sinus tachycardia
Sinus rhythm over 100/min: regular, with an upright P before every QRS.
Want a new strip every time? The ECG Drill in the app draws a fresh, measured example on every try and steers you toward the rhythms you miss. It's part of the Paramedic level, and you can try 5 strips a day free.
Try the ECG Drill