Decremental properties of a concealed nodoventricular pathway.

Introduction: The decremental properties of the nodoventricular pathway (NVP) are uncertain. Methods and Results: During short RP supraventricular tachycardia, a His‐refractory premature ventricular contraction (PVC) consistently terminated the tachycardia without atrial capture immediately after the PVC. Whereas a slightly earlier PVC failed to reset the subsequent His but terminated the tachycardia without atrial capture one cycle later. Conclusion: These observations are diagnostic of slow‐fast atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed‐NVP and can be explained by decremental properties in the NVP itself; greater prematurity of the PVC resulted in more decremental conduction over the NVP, causing the AVNRT termination one cycle later. [ABSTRACT FROM AUTHOR]