Example of His bundle antegrade and retrograde conduction.
The plaque shown is a 8×8 array with 300 um electrode spacing, which covers a 2.1 mm x 2.1 mm region of the endocardium. Regions not containing strong His activity are shown in gray. A) Conduction during sinus rhythm was in the antegrade direction. B) Conduction in the His bundle during VF was almost always in the retrograde direction. The example shown is during perfused VF.