A Fib aint no lie!

[George4]

My friend and I were discussing Atrial Fibrillation, and had a few questions that we could not find any answers to online or in other texts. If we could get some help on these subjects, it would be much obliged. Thanks!

According to ACLS protocols, if the patient is in A Fib and unstable, we understand that Sync Cardioversion is appropriate. At what rate is this pertinent to? 150+?

The most frequented example of using Syncronized Cardioversion in the classroom setting is in SVT > 150, with associated signs and symptoms (chest pain, hypotension, signs of shock, etc...). Do the same signs and symptoms apply to A Fib?

How often does a paramedic cardiovert A Fib in the field?

 

[JPINFV]

1. Rate is not the same as stable/unstable.

2. Especially if it's a new onset with unknown duration, DO NOT RUSH TO CONVERT the rhythm. Patients with new onset of unknown duration, especially if it's possible that it's over 48 hours, needs to be on anticoagulants and get an echo before rhythm conversion is attempted, least we start sending clots to the brain and lungs.

 

[George4]

If it is a known new-onset A Fib (lets say for argument's sake, less than 1 hour), with unstable presentation (for example, hypotension and s/s of shock), and rate of less than 150 (140, for example), can you cardiovert it?

Bottom line, is 150 a golden rate for cardioversion? or can you cardiovert lower rates given the s/s and presentation???

 

[truetiger]

It's a grey area....just like the rest of EMS. Ask 10 different paramedics and you'll get 10 different answers. Bottom line is this, if the patient is "unstable", do what you need to do. What is your impression of the patient telling you? I'm not going to cardiovert someone who's rate is 170 and they are having chest pain but otherwise look hemodymically stable. Now if their BP is in the toilet and they look like crap, then thats a different story.

 

[Nervegas]

If it is a known new-onset A Fib (lets say for argument's sake, less than 1 hour), with unstable presentation (for example, hypotension and s/s of shock), and rate of less than 150 (140, for example), can you cardiovert it?

Bottom line, is 150 a golden rate for cardioversion? or can you cardiovert lower rates given the s/s and presentation???

Known onset of < 48 hours? Yes, you can cardiovert it at any rate because it is unstable, rate does not define the stable vs unstable. There is no "golden rate", I have had a pt with afib at 130 be hypotensive and need SC and had one who was Afib with RVR @ a rate of 300 and talking to me just fine. Treat the s/s and immediate threats, don't zero in on the afib, don't get gung ho and cardiovert someone stable enough to make it to the ED, or withhold it on a PT who needs it. Like most of what we do, its a case by case basis and a judgement call.

 

[systemet]

If it is a known new-onset A Fib (lets say for argument's sake, less than 1 hour), with unstable presentation (for example, hypotension and s/s of shock), and rate of less than 150 (140, for example), can you cardiovert it?

Bottom line, is 150 a golden rate for cardioversion? or can you cardiovert lower rates given the s/s and presentation???

It's a risk/benefit equation. You can cardiovert as an attempt to convert the rhythm at pretty much any rate. But:-

* As JPINFV very clearly stated, the longer the patient is in a.fib, the greater the likelihood that rhythm conversion may result in embolisation.

* Cardioversion of all but the most unstable patients is going to require procedural sedation, which carries it's own risks.

* True life-threatening unstable a.fib is somewhat rare. You may meet many patients who are both unstable, and in a.fib at a high rate. But in practice, a fair number of these patients are actually compensating for another underlying disease process, e.g. dehydration, sepsis.

In many situations the patient is better served by an attempt to (i) control the rate medically, or a cautious approached where we (ii) monitor and drive to the ER, and let the MDs find the best solution.

------------------------

On a physiological note:

There is, and never will be any magical "golden rate". We know that CO = HR * SV, and we know that atrial fibrillation patients lack "atrial kick", the extra preload provided by active filling during atrial systole. At faster heart rates we already have a potential for stroke volume to decrease as filling time (i.e. ventricular diastole) decreases. This is further compounded when we lose atrial contraction. Add to this the potential for other underlying disease processes, e.g. pulmonary disease, ventricular hypertrophy, cardiomyopathy, prior infarction, prescription medication to control the a.fib that may have negative inotropic effects, and we can have further reductions in stroke volume. Individual patients will therefore have different stroke volumes at a given heart rate.

If we consider hypotension, we have the relation BP = CO * SVR. We know that lower cardiac output can be further compensated by increases in systemic vascular resistance. Admittedly this comes at the cost of an increase in afterload, which will decrease the ejection fraction and stroke volume. SVR may be affected by other disease processes, e.g. HTN, peripheral vascular disease, aortic stenosis, etc. It too may be affected by pharmacology, including many prescription antihypertensives, and other medication. It will be affected by the stress response, and by local autoregulation in different vessel beds under conditions of hypoperfusion. This too will vary on a patient by patient basis.

So you have multiple issues. A 30 year old guy, former football player, obese, incipient HTN, goes on a week-long bender on the all-inclusive to mexico and comes back with "Holiday heart" a.fib, is probably going to compensate very well at 150 bpm. The 89 year old urosepsis / early community acquired pneumonia patient with uncontrolled HTN, prior infarction, quad CABG, CHF, renal failure, a resting 6cm aortic aneurysm and a litany of complaints about the youth of today at 150 bpm may be close to death. Treatment for both will differ accordingly.

All the best.

 

[George4]

Thank you guys so much for this information! This is great to read thru. Definitely gave us a lot more to discuss. Thanks so much!

Feel free to elaborate on atrial fibrillation on this topic. It is a very interesting to read this info!

 

[Smash]

Systemet has covered everything well, but I would just like to second one of his comments.

If you see uncontrolled AF, look for a cause. The vast majority of people you see in AF will have it as their normal underlying rhythm, and their rate is up due to something else - sepsis in the elderly being the classic one. Rapid AF is usually just the elderly patients version of sinus tach.

Obviously AF can be the primary problem, but you will find that this is relatively rare.

 

[usafmedic45]

How often does a paramedic cardiovert A Fib in the field?

In 15 years, I have seen it done twice in the field. Atrial fibrillation is a pain in the *** to convert generally. Rate control is much easier, a lot safer and more effective.

 

[JPINFV]

Rhythm control is more effective than rate control. However, if rhythm control can't be maintained, then rate control becomes more effective and safer.

 

[usafmedic45]

Rhythm control is more effective than rate control. However, if rhythm control can't be maintained, then rate control becomes more effective and safer.

Well, in the field, withouth the benefit of TEE and patients being such poor historians, I would argue that controlling the rate is far safer and it tends to be a good way of immediately reducing the signs and symptoms that would lead most reasonable EMS providers to the idea of cardioversion.

 

[JPINFV]

Well, since you put it that way, I think I can AFFIRM your post.

 

[TomB]

True life-threatening unstable a.fib is somewhat rare. You may meet many patients who are both unstable, and in a.fib at a high rate. But in practice, a fair number of these patients are actually compensating for another underlying disease process, e.g. dehydration, sepsis.

In many situations the patient is better served by an attempt to (i) control the rate medically, or a cautious approached where we (ii) monitor and drive to the ER, and let the MDs find the best solution.

One of the best comments I've seen in this forum.

 

[NomadicMedic]

If you see uncontrolled AF, look for a cause. The vast majority of people you see in AF will have it as their normal underlying rhythm, and their rate is up due to something else - sepsis in the elderly being the classic one. Rapid AF is usually just the elderly patients version of sinus tach.

^ This. I've seen rapid Afib in several elderly PT's recently. They all have been septic and my first choice for treatment has been a fluid bolus. The pressure is too low for cardizem or any versed for sedation and they haven't been unstable enough for me to cardiovert without sedation.

Sometimes it's best to do less in the way of intervention.

 

[George4]

So as far as rate and rhythm control, I understand the rate control, being vagal/adenosine/cardioversion... When you refer to rhythm control, are you referring to a calcium channel blocker like Cardizem or some other drug (Dig)? How exactly does one control A Fib rhythmically in the prehospital setting? Im from California, and they didn't really talk about it too much. Maybe not in local protocols?

Thanks so much for the excellent information again folks. Really wonderful to come to a forum like this and be able to get my questions answered. Drawing from so many shared years of paramedicine will make me the best medic I can possibly become. Sincere thanks to all.

 

[MasterIntubator]

Never had to electrically cardiovert a-fib. But have dealt with new onset of rapid a-fib/a-fib with a ventricular response with associated signs ( CP, SOB ) with diltiazem. They have all responded well with that treatment. My decision to cardiovert will generally be when the pt no longer is mentating appropriatley...

 

[NomadicMedic]

Agreed. Cardizem is what we use to rate control afib, and cardioversion is, while not directly stated as such, reserved for only the most unstable of patients. I've only cardioverted afib with rvr twice, same patient both times.


Sent from my iPhone.

 

[usafmedic45]

I understand the rate control, being vagal/adenosine/cardioversion

Adenosine isn't going to do :censored::censored::censored::censored: to atrial fibrillation. Cardioversion isn't for rate control. It's for rhythm correction.

When you refer to rhythm control, are you referring to a calcium channel blocker like Cardizem or some other drug (Dig)?

Cardizem, amiodarone, beta blockers, and digoxin can be used for rate control. You seem to have your modalities exactly backwards.

How exactly does one control A Fib rhythmically in the prehospital setting? Im from California, and they didn't really talk about it too much. Maybe not in local protocols?

Amiodarone and cardioversion being the two big ones. It's not commonly done in the field. Conversion, unless the patient is literally dying, should never be done emergently prior to echocardiographic study.

 

[18G]

In Pennsylvania we can use diltiazem or verapamil for rapid Atrial fib (although have not seen an ALS service carry verapamil). For regular narrow-complex tachycardia we can also opt to use adenosine or diltiazem.

For wide-complex tachycardia, we are to consider adenosine first or use Lidocaine or Amiodarone. Does anyone else try adenosine first for wide-complex tachycardia?

 

[usafmedic45]

Does anyone else try adenosine first for wide-complex tachycardia?

That's been the policy everywhere I worked unless the patient was so unstable that cardioversion was warranted.