BBB VS vtach?

Cowboyardee · Dec 17, 2018

Lifeinthefastlane has a decent online tutorial on this. Take a look please. Unfortunately, it's not always a simple or easy dstinction to make.

First, I suggest being able to recognize bbb morphology. This is typically done in v1 and v6, using the mnemonic "william marrow." Morphology typical of a bbb tends to favor widened svt. Simple, extremely wide, or uni-polar morphology in your v leads tend to favor v-tach. Subtle differences matter here though - for example, an Rsr pattern in v1 is more likely to be v tach than rsR in the same lead.

The presence of capture beats, fusion beats, or av dissociation are good markers that you're looking at v tach in a fast, wide rhythm

A northwest axis tends to indicate v tach rather than wide svt.

A pulseless or profoundly compromised patient is more likely to be in V tach than widened svt, especially if no other causes of hemodynamic compromise are obvious. Just a rule of thumb though.

A child is more likely to be in svt than v tach. Another rule of thumb here.

There's more, but those are some of the most obvious indicators.

CCU BSN RN · Dec 17, 2018

If you're asking this question, I assume you want easy, fast answers for when you're in an acute clinical situation. As such, these are generalizations, not hard and fast rules:

1. If there's no pulse, it's VT

2. If it's fast, it's more likely VT. If the rate is 100-130, it's probably a bundle, but if it's 'slow VT', they're often stable in it, and you have time to get a 12 lead and the MD for a consult.

3. If the wide QRS is new and sudden, with a profound rate change, I treat it like VT unless I have reason to believe otherwise (hx of AF with RVR and BBB not present when in NSR)

Pheebz777, BSN, RN · Dec 18, 2018

You can still have a pulse while in VT. Not adequate perfusion but you still have a pulse. And there's pulseless VT.

To the OP, Are you a Tele Monitor Tech? Without a 12 Lead EKG and only looking at 1-2 leads on your monitor, if you recall VT's impulses are generated from the ventricles so you will always see wide mono morphic complexes. In BBB, there is still conduction from the SA node to the AV node and down the Bundle of His thus generating a better distinguishable QRS complex.

Now you have the aberrancy. Since one side of the bundle is blocked, the signal will bypass the Left or Right Bundle of His causing the signal to travel down the ventricular septum cell-to-cell instead of thru the normal pathway thus the widened QRS.

On slower rhythms this is easy to see. However when you have a tachycardic patient (or SVT) with a Left or Right BBB it almost always looks like VT, but remember there should be a discernible QRS, Rwave, or S wave that you might be able to identify as opposed to VT which will have none.