Is this PVC during refractory His ?
During the SVT, we notice that the patient has a PVC, but how can we tell whether it reaches the His refractory period or not?
We can see that the PVC causes fusion because the RV interval does not change, indicating that the His is indeed in its refractory period, which is reassuring.
We know that right ventricular pacing with advancement of the atrium suggests a septal or right-sided pathway.
Similarly, left ventricular pacing with advancement of the atrium indicates a left-sided pathway.
Here, the PVC has a right bundle branch block morphology and is negative in the inferior leads, suggesting it originates from the left ventricle.
Therefore, this confirms a left-sided accessory pathway