Figure 3.

Ladder Diagram Depicting a His-His Decrement During Atrioventricular Nodal Re-Entrant Tachycardia, as Shown in Figure 1B

This finding is postulated to result from conduction over another antegrade slow pathway with faster conduction and associated atrio-His shortening resulting in an upper common pathway block. Termination of tachycardia occurs in the next beat with block in both antegrade slow pathways. A = atrium; AVN = atrioventricular node; FP = fast pathway; His = bundle of His; LCP = lower common pathway; SP = slow pathway; UCP = upper common pathway; V = ventricle.