Termination, Advancement, and Delaying Responses to His Synchronous Premature Ventricular Contractions During Narrow QRS Tachycardia: What Are the Possible Mechanisms?

Figures

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  Figure 1:. A narrow QRS tachycardia easily induced by a PVC.

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  Figure 2:. The tachycardia was easily induced by PVCs during EP study (A) and electrocardiography monitoring (B). C: The intravenous adenosine terminated the tachycardia with a retrograde P-wave, which then easily started up again with a PVC, showing an incessant nature.

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  Figure 3:. A spontaneous His-refractory PVC during the tachycardia terminated the tachycardia without retrograde atrial activation.

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  Figure 4:. Whereas the atrial activation seems “delayed” without a change in the atrial activation sequence after the first Hr-PVC, it appears “advanced” without a change in the atrial activation sequence after the second Hr-PVC.

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  Figure 5:. Two H–H intervals were each equal to double the length of an H–H interval for both Hr-PVC cycles (based on measurement of the interval lengths of the two H–H intervals immediately before and after the Hr-PVCs).

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  Figure 6:. Ventricular overdrive suppression shows no entrainment but suggests dissociation of the ventricle from the ongoing tachycardia. The V-A-H-V response also excludes an AT.