Purkinje Fibers in Canine False Tendons: New Anatomical and Electrophysiological Findings

Figure 4

Electrophysiologic mapping of the endocardium using the DVM method. (a) Two 20-electrode mapping catheters were positioned at the LV septal endocardium from the upper septum to the apex. One mapping catheter (P1–P20) was stuck on one of the FTs, and the other one (P21–P40) was placed at the adjacent Purkinje network. Pacing point is located at the proximal end of FT (red star). (b) Lugol’s liquid staining in the dog’s endocardium: Purkinje fibers were dyed darker. (c) When pacing from the proximal FTs, at the cycle length of 400 ms, the conduction direction of Purkinje fibers contained in the FT was from the proximal to the distal end, and the conduction direction of Purkinje fibers on the apical endocardium was from the distal to the proximal end. After stopping the pacing, Purkinje fiber automaticity from FTs (the four to eight beats) was observed. (d) When pacing at a cycle length of 250 ms, decremental conduction of Purkinje fibers occurred, and the activation sequences of Purkinje fibers were the same as that of 400 ms pacing (c).