afib/bundle branch block

HI Everyone, I really need some help here figuring this out. Let's say a pt is in rapid afib and has a bundle branch block. How would this show up on the monitor, and how should this be treated? Would this be a wide complex tachycardia.. should it be treated as afib or vtach? I recently had this scenario. My 85 year old male pt had a history of afib. He also had copd, along with multiple other medical problems. When I came on shift his rate was 145-148. This was not new with him for this admission, with any activity his heart rate had been up to 160. His activity was changed from brp to cbr. He had an order for cardizem for sustained rate over 120. I immediately started the gtt ( had not been started by previous shift). The order was for 5mg/hr only -- cardiologist who ordered is very familiar with this pt and his hx. Slowly, his heart rate did come down to acceptable level. However, throughout the night with any activity on his part, even just sitting up in bed or coughing, his heart rate would go back up to 140-150. When his hr would elevate it kept coming up on the bedside monitor as pvc's and vtach. When his rate would slow you could clearly see the afib and a bbb. I got 2 stat ekg's on him on my shift and they did not show vtach or pvc's but rather ectopic atrial tachycardia. Any comments welcome. Thanks.

The appearance on the monitor would vary depending upon the lead(s) being monitored and the rate. There are many references which offer probabilities as to whether certain observed characteristics in certain leads suggest ectopy or abberrancy. And as you observed, at higher rates it may become difficult to appreciate atrial fibrillation since the complexes may appear regular.

This patient, however, was well known to the cardiologist as having chronic atrial fibrillation with a bundle branch block. And since the cardiologist wrote a standing order for the cardizem, he clearly anticipated the possibility of a rapid ventricular response during this hospitalization. And by knowing his patient, he was able to order what "works" best/safest to achieve adequate rate control (which would be the goal in this case).

There are cookbook answers/algorithms for treatment of wide QRS tachycardias of uncertain origin. But obviously it would be more efficient to know exactly what you are dealing with....patient Hx, EKG and expert consultation with a cardiologist are appropriate in that regard.

Without trying to be flip, if a-fib it should be treated as a-fib (possibly digoxin, cardizem, or commonly used amiodarone etc. depending on the patient). Likewise if v-tach then treat as v-tach (probably amiodarone).

Of course, I am assuming that the patient is tolerating the rate which in most cases they will below 150/min; a severely symptomatic tachycardia will require emergent cardioversion regardless of its origin.

Finally, I would be curious as to when this patient's rate first exceeded 120/min since at the time you assumed care his rate was 145-148 and no drip running. Rapid ventricular rates can appear quite suddenly. On the other hand if the patient was allowed to cruise in the 130s for a period of time without intervention, I would complete an occurence report. The gradual response to the cardizem gtt without a bolus would likely have been a non-issue had it been initiated when the patient was in the 120s as ordered.

THats such a good topic! Glasgow's right in that the patient has a known history of wide-qrs and a-fib so the monitor shouldn't bother you if it says 'pvc's or v-tach'.

The main way the monitor 'senses' pvc's/v-tach is by measuring the qrs width, so you'll see monitors mis-interpreting Bundle-branch-blocks all the time as v-tach or pvc's.... (yet another reason not to rely on machines...)

So... you know he has a-fib with BBB which is very helpful. The best way to differentiate (in this patient) by TELEMETRY if he's actually having runs of V-tach (rather than his baseling a-fib w/BBB) is to keep the leads in II and MCL (if 5 lead), or lead II if 3-lead. When you suspect V-tach, compare his bundle with an earlier base-line bundle. A simple way to differentiate is if the bundles have flipped (basically meaning upside down) or changed shaped drastically. If so, it COULD be v-tach. Also, in a patient with a significant cardiac history (he obviously does), V-tach will MOST LIKELY cause symptoms and he'll 'feel it'. (hypotension, dizzines, palpitations, etc.)...so you have to take that into consideration as well.

Another spin on this is that a person with a-fib and BBB can have a abberant (sp?) conduction...which means his bundle can periodically flip and/or change shape..but it's still a-fib!...making this mess MUCH harder to differentiate. Even on 12-lead, abberent a-fib with bbb, or fast a-fib w/bbb can be misinterpreted as V-tach. These patients can be frustrating!!

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(off the subject)The reason i'm interested in this issue is because there's been a debate among some of the icu-nurses where i work...

A common practice is that when a floor-nurse calls a code, or a 'Rapid Response' they'll apply defib-pads, (which many times is set at AED-mode). NOw, an AED that's seeeing a fast a-fib w/BBB can (just like more elaborate tele machines!) interpret this as v-tach and you'll get the AED-computer voice saying 'shock advized...charging..!, etc. Of course no-ones been inadvertantly defibrillated unneccesarily (where i work)...but there's always someone who hits the lottery... (sorry for the ramble!)..

Dinith

Interesting point about the AEDs. If the patient has arrested though, wouldnt it be appropriate to defibrillate?

I read a few holter monitors and have spent a lot of time trying to decifer between aberrant AF and VPC's. Nowadays I tend to call everything as of ventricular origin if i am not sure.

Literature tends to state that if you cant decifer between aberrant AF and VT, and the patient is symptomatic, they should be treated as VT as that is what the diagnosis is more likely to be.

Also, a quick question - what does gtt stand for? i am from Australia and am not familiar with the abbrev.

thanks.

Dinith

Interesting point about the AEDs. If the patient has arrested though, wouldnt it be appropriate to defibrillate?

I read a few holter monitors and have spent a lot of time trying to decifer between aberrant AF and VPC's. Nowadays I tend to call everything as of ventricular origin if i am not sure.

Literature tends to state that if you cant decifer between aberrant AF and VT, and the patient is symptomatic, they should be treated as VT as that is what the diagnosis is more likely to be.

Also, a quick question - what does gtt stand for? i am from Australia and am not familiar with the abbrev.

thanks.

gtt refers to drops....it's an abbreviation for guttae (Latin)

The main way the monitor 'senses' pvc's/v-tach is by measuring the qrs width, so you'll see monitors mis-interpreting Bundle-branch-blocks all the time as v-tach or pvc's.... (yet another reason not to rely on machines...)

I have found this to be true. A BBB widens the QRS, and the monitor may read it as VT or PVCs.

Was the rhythm regular or irregular when it was above 120?

Afib with BBB can show wider QRS complexes at higher rates but the rhythm should still be irregular. If so then the rhythm was probably still afib. Vtach shouldn't be irregular.

Sometimes you have to throw the monitor interpretation out the window. I had a patient last week with a tachy arrythmia and when I did an ECG the interpretation from the machine was sinus tachycardia even though I decided it was aflutter (and so did the cardiologist).

Dinith

Interesting point about the AEDs. If the patient has arrested though, wouldnt it be appropriate to defibrillate?

.

You're correct. But, the situation i was referring to was (hypothetically) for example a copd patient w/a history of AF w/BBB who runs into trouble/shortness of breath from his lung disease...who could (would probably) be tachycardic (even >120). Slap an AED on this person and (just like telemetry) it could 'see' v-tach and advise a shock. Of course most acls/critical-care/code-type nurses would switch the AED off and just look at the monitor...but...it's not too far out to envision a freaked-out floor nurse (on some non-tele unit) doing what the AED asks...before the code-team/RRT (rapid-response-team) arrives. This is the type of situation i was referring to. You see, when a patient on the floors runs into trouble (where i work) it's kinda standard for them to place the hands-off pads and the defib on the patient before/while calling a RRT or code. These defibs are many times set at an AED mode. It's usually a good practice....but. Hope i didnt confuse you.

Good thread, some things to remember:

-Any history of BBB? A new LBBB needs to be treated until proven that they have a hx of LBBB--ALWAYS GOOD TO KNOW IF a pt. has a hx. I always tell people who have an abnormal baseline EKG to carry a copy w/ them at all times.

-Look at the pt. not the monitor. Too many people are focused on rate. 150 bmp is not a MAGICAL NUMBER, if you have someone in 130's and is symptomatic TREAT IT!!!! Beta bloackers obviously slow HR but you can still have a VT w/ a rate less than 150 bpm.

-Lastly, it is good to monitor in two leads at a given time.

You're correct. But, the situation i was referring to was (hypothetically) for example a copd patient w/a history of AF w/BBB who runs into trouble/shortness of breath from his lung disease...who could (would probably) be tachycardic (even >120). Slap an AED on this person and (just like telemetry) it could 'see' v-tach and advise a shock. Of course most acls/critical-care/code-type nurses would switch the AED off and just look at the monitor...but...it's not too far out to envision a freaked-out floor nurse (on some non-tele unit) doing what the AED asks...before the code-team/RRT (rapid-response-team) arrives. This is the type of situation i was referring to. You see, when a patient on the floors runs into trouble (where i work) it's kinda standard for them to place the hands-off pads and the defib on the patient before/while calling a RRT or code. These defibs are many times set at an AED mode. It's usually a good practice....but. Hope i didnt confuse you.

I can envision that situation too Dinith88. Good point!

The appearance on the monitor would vary depending upon the lead(s) being monitored and the rate. There are many references which offer probabilities as to whether certain observed characteristics in certain leads suggest ectopy or abberrancy. And as you observed, at higher rates it may become difficult to appreciate atrial fibrillation since the complexes may appear regular.

This patient, however, was well known to the cardiologist as having chronic atrial fibrillation with a bundle branch block. And since the cardiologist wrote a standing order for the cardizem, he clearly anticipated the possibility of a rapid ventricular response during this hospitalization. And by knowing his patient, he was able to order what "works" best/safest to achieve adequate rate control (which would be the goal in this case).

There are cookbook answers/algorithms for treatment of wide QRS tachycardias of uncertain origin. But obviously it would be more efficient to know exactly what you are dealing with....patient Hx, EKG and expert consultation with a cardiologist are appropriate in that regard.

Without trying to be flip, if a-fib it should be treated as a-fib (possibly digoxin, cardizem, or commonly used amiodarone etc. depending on the patient). Likewise if v-tach then treat as v-tach (probably amiodarone).

Of course, I am assuming that the patient is tolerating the rate which in most cases they will below 150/min; a severely symptomatic tachycardia will require emergent cardioversion regardless of its origin.

Finally, I would be curious as to when this patient's rate first exceeded 120/min since at the time you assumed care his rate was 145-148 and no drip running. Rapid ventricular rates can appear quite suddenly. On the other hand if the patient was allowed to cruise in the 130s for a period of time without intervention, I would complete an occurence report. The gradual response to the cardizem gtt without a bolus would likely have been a non-issue had it been initiated when the patient was in the 120s as ordered.

I know you mention 'depending on the pt' in your reply, but I just want to remind all to be leary of amiodarone in COPD pts's due to the risk of pulmonary fibrosis. This is mostly with longer term use but problems can occur during the bolus dosing too. (just my $0.02)

Also I agree with you on the cardizem gtt w/o a bolus--In this case the MD knew the pt but I've seen this order before from hospitalists who know nothing of the pt hx. If your serious about rate control order the bolus, repeat if needed and start the drip at 10ml/hr titrating to effect within drug limits. Another pet peeve...d/c ing cardizem gtt after pt converts and NOT ordering PO to maintain rate control/SR:banghead:

Amio is OK for short term, in hospital dosing. Any immediate pulmonary effect during administration is from an immune reaction, not pulmonary fibrosis.

I wouldn't discharge someone on maintenance amio w/a h/o lung disease, but for acute conversion it's OK....