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Ventricular fibrillation on an ECG strip

Chaotic waves of varying size, with no P waves, QRS complexes or T waves.

What to look for

Chaotic, irregular deflections of varying size and shape at 150-500/min, with no P waves, QRS complexes or T waves. There's nothing to measure. Coarse VF has large waves, and the longer VF lasts, the smaller they get, until it becomes fine VF. That's the one that can be mistaken for asystole.

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 1 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
No QRS complexes to count
Rhythm
Chaotic, with no complexes to measure
P waves
None
P to QRS
No P waves and no QRS complexes
PR
None to measure
QRS
None
Waves
4 mm top to bottomCoarse
Example 2 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
No QRS complexes to count
Rhythm
Chaotic, with no complexes to measure
P waves
None
P to QRS
No P waves and no QRS complexes
PR
None to measure
QRS
None
Waves
6.2 mm top to bottomCoarse
Example 3 · lead II · 6 seconds
II25 mm/s · 10 mm/mV
Rate
No QRS complexes to count
Rhythm
Chaotic, with no complexes to measure
P waves
None
P to QRS
No P waves and no QRS complexes
PR
None to measure
QRS
None
Waves
7.7 mm top to bottomCoarse

Don't confuse it with

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

Where the criteria come from

Others in the Ventricular group