How come there is no P wave in ventricular fibrillation?

ECG. There may actually be a P wave in some vfib. You won't see it because of the vfib waves.
P waves are atrial. "p" wave are a finding on the ECG (electrocardiogram) which represents atrial contraction. During ventricular fibrillation there is no organized atrial activity and therefore there will be no P wave generated.

Related Questions

Is there a P wave in ventricular fibrillation?

Not visibly.. There is usually atrial activity, either the occasional retrograde atrial activation, or just the normal sinus rate progressing along unaffected by the vf. However, with the continuous ventricular activity in vf, it would typically be impossible to make out a P wave on the surface ekg. When we have catheters in the heart (during an ep study) we see the atrial activity in vf.
No... There is no organized rhythmn in ventricular fibrillation so no P wave is present. There is also no qrs complex present. There is no blood flow as the heart is quivering so the patient is clinically dead. The heart needs to be shocked as quickly as possible to hopefully restore a normal rhythmn.
Vf. They are masked by extremely rapid electrical storm in the heart, so can't see them in ECG.