This week’s electrogram interpretation:
What is the most likely rhythm?
Answer
Junctional
- Notice how all of the A’s and V’s appear to line up and happen at approximately the same time. If the impulse originates for the AV junction, it will travel in both directions, retrograde to the atrium and antegrade to the ventricle.
- The AV node has an intrinsic automaticity rate of 40-60 bpm. This will be seen with a junctional escape rhythm.
- A junctional rhythm will produce a narrow QRS complex since the activation is utilizing the normal conduction system to the ventricles (unless there is an underlying BBB).
- Inverted P waves will be observed in the inferior leads (II, III, & aVF) as the impulse is depolarizing the atria from low to high – away from the positive pole at the foot.
- Junctional tachycardia may be observed with digitalis toxicity, cardiac surgery, acute myocardial infarction, or isoproterenol infusion.
- Isoproterenol, or Isuprel, enhances the AV junction automaticity. This is why we observe junctional rhythm with Isuprel in the EP lab, such as in this example.
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For more information: EP Essentials – Understanding EP: A Comprehensive Approach
