Example of His bundle antegrade and retrograde conduction.

<p>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. <b>A)</b> Conduction during sinus rhythm was in the antegrade direction. <b>B)</b> Conduction in the His bundle during VF was almost always in the retrograde direction. The example shown is during perfused VF.</p>