What type of pacing is being performed in the following electrogram?
What is your interpretation?
Answer
AP ERP
Each impulse in the drive train (S1) captured the atrium and conducted to the ventricle. However, notice the wide QRS complex due to the delta wave which demonstrates activation down an accessory pathway. On S2, the impulse still conducted to the ventricle but through the AV node. The A to V interval is longer and there is no delta wave. The effective refractory period of the accessory pathway has been reached and it is no longer able to conduct.
More Information:
For more information, please see: EP Essentials – Understanding EP: A Comprehensive Approach – section on accessory pathways.
