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.