Ventricular fibrillation is the most dangerous arrhythmia, right?

[Knicks]

Is it true that atrial fibrillation is the most common arrhythmia, and that ventricular fibrillation is the most dangerous/fatal arrhythmia?

(cuz I read somewhere that atrial fibrillation was actually the most dangerous).

Feel free to elaborate in your responses.

Thanks.

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[sd1984]

When a heart goes into V-fib, effective pumping (we are talking about ventricles here) of the blood stops.

 

[McGillGrad]

Vfib = death due to no CO

Afib = most common but only fatal at such a high frequency that nothing gets past the AV node (and even then you have a basal ventricular rate which is better than zero, but not by much)

 

[JPort]

just remember how many people in this world drink alcohol and then think of its relation to afib.

 

[ENThopeful]

Vfib = death due to no CO

Afib = most common but only fatal at such a high frequency that nothing gets past the AV node (and even then you have a basal ventricular rate which is better than zero, but not by much)

yikes no CO must be dangerous

 

[McGillGrad]

yikes no CO must be dangerous

 

[ENThopeful]

whoops i thought you meant carbon monoxide and not cardiac output for some reason. it was late

 

[Knicks]

Thanks for the replies, everyone.

 

[Rendar5]

afib is not an inherently dangerous arrhythmia. And I"m not sure what mcgill was trying to say about it's frequency being too high to get past the AV node? The only way it doesn't get past the AV node is if you have an AV block on top of it. In that case, the danger is not from the afib but rather from the Mobitz type II or the tertiary block (primary block and Mobitz type I are not particularly dangerous rhythms) There are two major dangers of afib:

1. as the atria have effectively lost their kick, the person has blood stasis in this chamber, allowing for thrombus to form. This thrombus may cause emboli, resulting in stroke. Thus, patient's in afib require anticoagulation to reduce their risk of emboli and resultant stroke.

2. afib with rapid AV response is dangerous because you may have a tachycardia that is too rapid for effective pumping and too rapid for coronary artery filling (which occurs during diastole). For this reason, people in afib may need to take a medicine that slows AV conduction such as a CCB or a BB.

Third, there is no evidence that rhythm control is necessary for afib. Sometimes they will cardiovert a younger person with "holiday heart" after ensuring no thrombus has formed, because otherwise he will not be able to be as active as he wants to be (hard to be a runner if you're losing atrial kick). Rather, emphasis is on rate control and anticoagulation.

 

[Knicks]

afib is not an inherently dangerous arrhythmia. And I"m not sure what mcgill was trying to say about it's frequency being too high to get past the AV node? The only way it doesn't get past the AV node is if you have an AV block on top of it. In that case, the danger is not from the afib but rather from the Mobitz type II or the tertiary block (primary block and Mobitz type I are not particularly dangerous rhythms) There are two major dangers of afib:

1. as the atria have effectively lost their kick, the person has blood stasis in this chamber, allowing for thrombus to form. This thrombus may cause emboli, resulting in stroke. Thus, patient's in afib require anticoagulation to reduce their risk of emboli and resultant stroke.

2. afib with rapid AV response is dangerous because you may have a tachycardia that is too rapid for effective pumping and too rapid for coronary artery filling (which occurs during diastole). For this reason, people in afib may need to take a medicine that slows AV conduction such as a CCB or a BB.

Third, there is no evidence that rhythm control is necessary for afib. Sometimes they will cardiovert a younger person with "holiday heart" after ensuring no thrombus has formed, because otherwise he will not be able to be as active as he wants to be (hard to be a runner if you're losing atrial kick). Rather, emphasis is on rate control and anticoagulation.

wow, thanks a lot for that in-depth, informative reply. 👍

Quick question though, the blood stasis may lead to thrombus formation, as you said. Wouldn't that happen in v.fib too?

I just want to ingrain these arrhythmias in my head.

Thanks

 

[lord_jeebus]

wow, thanks a lot for that in-depth, informative reply. 👍

Quick question though, the blood stasis may lead to thrombus formation, as you said. Wouldn't that happen in v.fib too?

I just want to ingrain these arrhythmias in my head.

Thanks

I think your patient will die before the v. fib induced thrombus gets a chance to develop.

 

[Captopril]

And I"m not sure what mcgill was trying to say about it's frequency being too high to get past the AV node?

If the frequency of firing of the SA node is too high, the depolarization can't be transmitted through the AV node to the ventricles because the refractory period of the previous AV nodal stimulation is still in play....



....I think.

 

[TexasTriathlete]

asystole is also a dangerous rhythm

 

[Scaredshizzles]

If the frequency of firing of the SA node is too high, the depolarization can't be transmitted through the AV node to the ventricles because the refractory period of the previous AV nodal stimulation is still in play....



....I think.

Yes, but it is not like it is completely blocked, some of the impulses are. The reason AFlutter has such a predictable rate of ~150 bpm is because the fastest a conduction current can spread through at atrium is about 0.02 seconds (300 bpm at a regular rate). 300 is indeed too fast a rate for the AV node, and since it is a regular rate, exactly every other beat gets blocked. But obviously you can have SA node conducted ventricular rates around 180-200, it is not uncommon. And re-entry currents can be even faster.

 

[a winner is you]

asystole is also a dangerous rhythm

Well technically, asystole is not a rhythm at all.

 

[Rendar5]

wow, thanks a lot for that in-depth, informative reply. 👍

Quick question though, the blood stasis may lead to thrombus formation, as you said. Wouldn't that happen in v.fib too?

I just want to ingrain these arrhythmias in my head.

Thanks

yeah listen to the poster who posted after this. I believe the AFib associated thrombus takes 48 hours to form, so if it's confirmed new onset afib (rarely can it be confirmed that it is new-onset since afib is not a particularly noticeable rhythm) you can shock out of it. I'd need to double check the literature though. V. Fib = sudden death as does any other non-perfusing rhythm. The purpose of shocking someone (defibrillation) is to stop electrical activity so that the heart resets rhythm. That's why we shock vfib patients.