Fig. 3

Histochemical findings after radiofrequency ablation in left atrium. a Left dorsal view of pressure-inflated sheep heart stained for AChE to demonstrate the epicardial nerves (white arrows) and ganglia (white arrowheads) on the dorsal left atrium, coronary sinus, and on the left dorsal ventricle. In the panel (b), the enlarged area boxed in the panel (a) illustrates the epicardial neural structures that were sampled and examined applying immunohistochemical method. c The dorsal left atrial area topographically identical to the boxed area in panel (a) 12 months after the epicardial RFA at the root of left and middle pulmonary veins (shown as dashed area on panel a). Note the epicardial nerves (white arrows) and ganglia (white arrowheads) that are evidently less histochemically positive for AChE following RFA at the roots of pulmonary veins. Panels (d-i) illustrate the transverse sections of the epicardial nerves that were immunohistochemically stained for PGP 9.5 (green color) and TH (red color) in control samples (d-f) and one year after RFA (g-i). Note the evidently lesser density of nerve fibers (positive for both the PGP9.5 and TH) in the experimental group nerves compared to the controls (panels e-f vs. h-i)