An extremely irritable ventricular focus may cause impulses to fire in a chaotic manner that stimulates the ventricles to begin fibrillating (quivering). VF is a lethal arrhythmia. 

VF has a distinct pattern that makes it the easiest arrhythmia to identify. There are no waves or complexes to read, just an extremely chaotic fibrillatory pattern (see Figure 6.6).

Related Video – ECG Rhythm Review – Ventricular Fibrillation

Figure 6.6. Ventricular Fibrillation

Ventricular Fibrillation ECG

Characteristics of Ventricular Fibrillation

1. Rhythm is irregular and chaotic, with no discernible ventricular waves or complexes 
2. Rate cannot be determined because the rhythm is chaotic, with no discernible waves or complexes
3. P waves are not present because the rhythm is ventricular in origin
4. PR intervals are not measurable because the rhythm is ventricular in origin 
5. QR complexes are chaotic with no discernible waves or complexes 
6. No pulse