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Ventricular Fibrillation


Ventricular Fibrillation

Ventricular fibrillation or VF occurs when there are uncoordinated contractions within the ventricles of the heart. The primary cause of VF is hypoxia (lack of oxygen) to the heart muscle which causes hyperirritability in the cardiac muscle tissue.

As a result, multiple muscles cells within the ventricles simultaneously fire as pacemakers causing a quivering or fibrillation that is ineffective for adequate cardiac output.

The two images above show what ventricular fibrillation will look like on a EKG rhythm strip.

VF can rapidly lead to heart muscle ischemia and there is a high likelihood that it will deteriorate into asystole.

Ventricular fibrillation is treated using the left branch of the puslesless arrest arrest algorithm. Click below to view the pulseless arrest algorithm diagram. When done click again to close the diagram.
Pulseless Arrest Algorithm Diagram.

Ventricular fibrillation is always pulseless and must be confirmed by EKG or defibrillator monitor. Defibrillation is the treatment of choice and should occur as soon as possible.

The video below shows an example of what ventricular fibrillation will look like when you see it on the defibrillator monitor. Please allow several seconds for the video to load.

Use the Megacode Simulator

  40 Responses to “Ventricular Fibrillation”

  1. If it is Vfib is pulseless, then why is it shockable? Why wouldn’t we follow right side of algorithm?

    • VF and Pulseless VT are treated using the left branch of the pulseless arrest algorithm. Both VF and pulseless VT respond quite well to defibrillation and the left branch of the pulseless arrest algorithm has proven to be the most effective method of treatment for VF.

      Kind regards,

      • Well why call it “pulseless VF?” Is there such a thing as VF with a pulse?!? When you put “pulseless” in front of VF/VT it confuses students new to ACLS. When new students try to figure this out for the first time seeing “pulsless” then advising a shock is confusing, since Pulseless Electrical Activity dosnt require a shock. Its ok to remind people that VF/VT patients wont have a pulse, but putting “pulseless” in the title will lead to unnecessary confusion between VT/VF and PEA. (I know a little studying will clear this up but I can see how confusing and frustrating this can be for first timers.)

      • I’m not sure where you saw pulseless VF. VF is always pulseless. In several places I have written Pulseless VT/VF and this means pulseless VF and VF.
        You will use defibrillation on pulseless VT. You will not use defibrillation on VT. VT may have a pulse and in the case that it does, you will use synchronized cardioversion. You have to clarify on whether you are dealing with pulseless VT or VT.
        I like to explain it by stating that Pulseless VT and VF are the two exception to the rule when it comes to PEA. This is why there are two branches to the pulseless arrest algorithm. The left branch for Pulseless VT/VF and the right branch for PEA/Asystole.
        Thanks for helping to clarify.

        Kind regards,

  2. this site is really helpful..:) i just wanted to ask something.. is it safe to deliver a shock when the patient is hooked with oxygen?

  3. By far the best ACLS tutorials! Lots of great tips on how to distinguish rhythms (especially the heart blocks) and explanations that are simple and easy to remember. Thank you for all the time and energy you put into your work. It makes my job of passing ACLS easier.

  4. I’m new at this. How can you distinguish between pulseless ventricular tachycardia and ventricular fibrillation on an ECG strip?

    • Ventricular fibrillation will be very disorganized and will not have a pattern. Also, you will not be able to determine the heart rate because the rhythm is disorganized.

      Ventricular tachycardia will have a very rapid rate which usually greater than 180/min. The rhythm will appear organized and you should be able to count the beats, but the rate will be extremely high.

      I would encourage you to review the above page and also the link below:

      Kind regards,

  5. I am a new grad and my first ACLS course is coming up very soon!! I want to pass! So far I love the videos and information available. Thank you

  6. The videos are great… really gets some adrenaline going!

  7. My goodness! This is shocking! Please keep up this beautiful, well constructed helpsite. Out here in the boonies we need the help. THANKS!

    • lol shocking har har :) i’m enjoying learning with the discussions underneath, and i’m enjoying this too. resident in fam med doing emerg

  8. This is site is definitely very helpful and i hope that it remains helpful in future. I love this site, thank you so much.

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