Ideally, ventricles receive stimulus to contract from one source. If there are multiple foci giving impulses, the contractions will be weak, rapid and ineffective, leading to loss of cardiac output from the ventricles.
If the waves on the ECG have low amplitude, we call it fine VF. See the image below (Source – wikipedia)
If the waves on the ECG have bigger amplitude than fine VF, we call it coarse VF. See the image below (Source – ecgpedia)
Ventricular fibrillation is a state of cardiac arrest. The patient will not have a palpable pulse.
When you spot such an ECG on the monitor, first thing to consider is defibrillation. But start CPR while you prepare for shocking.
More on CPR and defibrillation in next lessons.