Figure 11.

Figurative illustration of unusual pathways. Mahaim fibers are true atrial ventricular connection, however, the connection occurs through an AV node and Hispurkenje-like structure (Mahaim fiber). Fasciculoventricular tracts are not true accessory pathways, but rather “breaches in the insulation” of the proximal His bundle and right bundle region such that early activation of the basal portion of the right ventricle occurs with a short H-V interval and a suggestion of preexcitation. Nodal ventricular and nodal fascicular fibers are rare accessory pathways that may participate in tachycardia (see text for details).