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EKG Junctional Rhythms

Terms in this set (15)

"If the AV junction is the pacemaker, the impulse will travel retrograde to the atrium. Remember that electricity goes every direction at once, so it's going to shoot down the bundle of his into the ventricles but it's also going to shoot to the atrium to depolarize them. If the P-wave is visible, it is ALWAY inverted in lead 2. Remember that the normal sinus rhythm the atria fired, QRS fired, then we a T-wave and it would go on from there. But now that it is going backwards, the P-wave will be upside down and everything else will stay normal. The PR interval will get shorter because there is no longer the nice long delay of the AV node because the delay is getting eaten up by the electricity going in other directions. Remember electricity is normally going towards the positive electrode in lead 2 so it will normally show a positive P-wave. So, when it is going backwards it makes sense why it's inverted.
The thing here is there is a lot of cells and the bundle too, so you tend to only see the inverted P-wave if it's one of the cells close to the Atria that takes over the pacemaker. This gives the Atria time to repolarize because most of the delay is still there. If it's one of the cells further down, the inverted P will still be there but it will more than likely be buried in the QRS. This is why we don't usually see a P-wave. "

*Conduction through the ventricles is normal because the right and left bundle branches are acting as normal. The problems with the heart are much higher up so the junction is taking control."

-When the AV junction takes over pacemaking responsibility, the atria and the ventricles will be depolarized at nearly the same time because the impulses spreads in two directions at one time.
*Junctional Bradycardia Interpretation:

*Rough Rate = Very Slow (Long R-R)

-Rhythm (R to R) = Regular
-"Whenever part of the junction has taken over the pacemaker of the heart it will be a regular rhythm. Which ever part of the junction decides to take over will and start firing off at it intricate rate."

Rate (Use Triplicate) = < 40 bpm
-Because it's a rate under 150.

P Waves = Inverted or Absent; may appear before or after QRS

PRI = < .12 - IF the P Wave precedes the QRS
-"If there is a P-wave to count the PRI, it will always be less than 0.12. It cannot be normal because no matter where in the AV junction it starts, some of the delay is removed because it goes in both directions instead of having to travel the entire way through. It's like starting in the middle of the road, both are going to be quicker because they don't have to walk to the full distance."

QRS = .08 - .12; Consistent Morphology
-"The QRS will be consistent and normal. By the time the ventricles fire, they fire through their normal mechanisms through the bundle branches and the purkinje fibers. This does not effect the ventricles at all. All the ventricle power is reserved minus the atrial kick."
^"This is even if the P-wave is before the QRS. The atria fired back but it wasn't pushing blood into the ventricles so much as it was slowing blood return down to the ventricles, so we reduced cardiac output by removing ventricular stroke volume AND we have a low HR. You will not find these people hypertensive. You have two decreases in cardiac output."