Ventricular Fibrillation V-fib is a cardiac arrest rhythm. It will NEVER have a pulse associated with it as the ventricles are quivering or "fibrillating," not contracting. Survival from this lethal rhythm requires immediate CPR, defibrillation, and ACLS procedures. V-fib is characterized by chaotic indistinguishable waveforms. The waveforms will range from large/coarse to small/fine. V-fib will not feature a P-wave, QRS complex, or T-wave.