What are we doing?
A 35-year-old patient is in the EP lab with complaints of palpitations. A two-catheter study is being performed with a decapolar CS and a deflectable quad for the His and RV applications.
What test is being performed in the following electrogram and what is your interpretation?
Answer:
This is an example of parahisian pacing. This pacing maneuver is used to help differentiate AVNRT and AVRT with a septal pathway.
This is performed by pacing the HIS catheter at high output. A narrower QRS complex is observed with HIS capture, the pacing mA will then be decreased until a wide complex is observed.
A measurement is then made from the Stim to A on both a narrow & a wide beat. If the wide QRS Stim to A measurement is longer than on the narrow complex, there is no evidence of the accessory pathway. Evidence of the presence of a septal pathway is demonstrated if the wide QRS Stim to A measurement is the same as on the narrow QRS paced beat.
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