Bundle Branch Block

[uglyEMT]

Ok I was on a call the other day and heard the term Bundle Branch Block. Well it made me think and I have been researching it for a few days now and am looking for help.

I have read some literature about it. My understanding is that it is damage to the nodes that control the muscles of the heart and is noticed on ECG as a QRS response lasting longer then 120ms. The damage is brought on by MI, heart surgery, or coronery disease.

Now for my question, is there anything that can be done in the prehospital environment to stabilize the patient? What can happen to the patient during transport ie MI or other potentially fatal outcomes?

I have a sample ECG print out from a book but not the patients actual readout.

Just looking to understand more thats all. At the time after the call I was discussing this with the medic and she got another call so it was cut short. Just wondering from a real world perspective vs a book.

Thanks in advance.

[JTpaintball70]

I don't think I've ever seen anyone treat an asymptomatic new onset BBB. Usually if it's new onset and there's symptoms, the symptoms get treated (Ie: CP=MONA)

[EMT155]

By definition, a BBB is a delay of conduction down the left or right bundle branch. Many people have this condition and live totally asymptomatic lives. To the best of my knowledge, we have no protocols dealing with the asymptomatic version here in CNY. This can change by state and region depending on your medical director. Patients with cardiac symptoms should be treated with the appropriate protocols for your region dealing with the symptoms (ie: chest pressure radiating, Systolic over 90, give a baby aspirin and a NTG) If i were to put a patient on the monitor as a precaution with no cardiac complaints and saw it, i would probably question them a little harder along the lines of cardiac history, but other than giving them O2, not much to do other than let the ED staff know.

Issues can arise from conduction issues between the SA and AV nodes, or if there is a complete block somewhere along the way as it can and will decrease the effective contractility of the heart as a muscle. Again, refer to local protocols for treatment options.

Here is a good explanation of the conduction system of a regular, healthy heart: Linkage

Here is a great read on Arrhythmias, including AV blockages: Linkage

Also going to attach a pic of the conduction system for you

I used to work as a cardiac tech in ICU, and the whole thing just amazes the hell outta me. I'm such a cardaic geek hope this helps you out some.

Jim

[uglyEMT]

Thanks for the tips guys. This place rocks. I have some more links now to go through and read up on.

As far as the pt w/ the BBB yes he had an extensive cardiac history and thats what the call was for.. "crushing chest pain w/ worst headache of my life". Before ALS got onboard we did follow protocol and got one NTG onboard the patient. Other then that it was 15lpm via HC NRB.

Being I never heard that term used by medics before it got me wondering.

Time to read up more! But basically there really isn't anything that can be done prehospitally for a BBB we just have to treat the other symptoms and notify the reciving facility of our findings. Gotcha.

edit was for formatting issues. no changes were made.

Edited December 14, 2010 by UGLyEMT

[fiznat]

A bundle branch block is a dysfunction in the normal depolarization pathway in the ventricles. Generally, the electrical signal starts towards the top of the heart and propagates downward and outward through "bundles" of fibers. Ideally, this propagation should be fast and uniform so that the corresponding contraction of the heart muscle is as efficient as possible. Sometimes, though, damage to the nerves or ischemia (lack of oxygen) in specific parts of the heart can interrupt or delay these signals, and you can get all kinds of "blocks" in the signal. These blocks can be acute or chronic. Lots of people have chronic bundle branch blocks, but new BBB is one sign of a possible acute cardiac problem. By itself, though, (as in, without any other signs or symptoms of an acute illness) BBB isn't very meaningful and doesn't require treatment.

Bundle branch block is also important in ECG interpretation in that it alters the "ST segment," which is the portion of the ECG that we use to identify acute MIs (heart attacks). In left bundle branch block especially, the block can be bad enough so that it is almost impossible to tell (on the ECG) whether or not a heart attack is happening. There are of course other parts of our assessment and a few tricks to alleviate this issue.

As far as the ECG you posted, there is a definite acute inferior STEMI (heart attack), but I'm not seeing too much bundle branch block. There is rSR' in V1, but the QRS is normal width. Maybe a bit of an incomplete Right BBB (RBBB), but not the best example of BBB in general.

Edited December 14, 2010 by fiznat

[uglyEMT]

Sorry about the image fiznat it was from an ECG website I was researching BBB on. I will see if they have a better example. Thanks for the heads up. I dont read ECGs so I didnt realize it was a poor example.

One thing I have to admit though is while researching this I do want to get a book and learn to read the ECG! Even though I wont be able to use the knowlege "officially" at least I will be able to understand what the paramedic sees on his / her LP12. (side note: after some teaching from a medic friend I did learn to place all the pads for the leads and have assisted the medics in doing so )

Thanks also for the information regarding the movment of electrical discharge in the heart. Reading the literature it does get somewhat confusing, I still need lay terms sometimes, but Im getting there.

edit to post new ECG readout. No new content added

Edited December 14, 2010 by UGLyEMT

[fiznat]

No problem! You should know though that regardless of what ECG interpretation book you get, that knowledge will be incomplete without the anatomy and physiology that is intertwined with all of this stuff. Medicine isn't a fungible commodity that can be truly appreciated a la carte. If you are interested in this stuff you should really think about going to paramedic school to get the whole story. I promise it will be extremely interesting and open up new worlds for you and your patients.

[uglyEMT]

Unfortunatly paramedic school is not in the cards for me. It would be great to do but time, my job, and life wont allow me too. Plus in my area all ALS is hospital based so I wouldn't get to use the skills anyways.

I understand about medical knowlege not being a la carte. Just seems interesting to me now and gives me a way to grasp some more knowlege. At least I will be able to understand the medic better LOL

[spenac]

http://ambulancedriverfiles.com/2007/06/sex-relationships-and-the-cardiac-conduction-system/

[EMT155]

If you're going to be studying up, a great text that i refer back to a lot still is the Brady book on Arrhythmias.

Linkage: http://www.bradybooks.com/store/product.aspx?isbn=0135002389

Great info there.

There is also a wealth of info on the net for casual reading and a few places where you can get practice ECG's too.

Best of luck!!

Jim