This week’s electrogram interpretation:
What is observed in the following electrogram?
The channels labeled A – D (green, teal, red, yellow) are recording from the HD grid (high-density mapping catheter) in the LIPV.
This was recorded while performing pulmonary vein isolation.
Answer
Exit Block
- On this patient, pulmonary vein isolation was performed (PVI) with an RF catheter. The catheter in the vein is an HD Grid mapping catheter (High Density).
The impulse originated in the pulmonary vein but was unable to conduct to the LA. Notice how the ectopic PV impulse does not affect the coronary sinus rate.
- This demonstrates exit block as the impulse was unable to “exit” the vein. This is an excellent endpoint for PVI. This demonstrates that if that patient’s atrial fibrillation is due to firing on the LIPV, this ectopic firing may no longer conduct to the atrium and cause AF.
This is a PV view of a 3D rendering of the left atrium. The red dots represent the ablation lesions during a segmental approach (vs. WACA). The HD grid is within the left inferior pulmonary vein. Due to complete pulmonary vein isolation, the impulse was unable to conduct to the left atrial body.
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If you like this, find hundreds of electrograms to interpret in our Understanding EP workbook – included in the Understanding EP book set.
For more information: EP Essentials – Understanding EP: A Comprehensive Approach
