Electromicrographs of left atrial cardiomyocytes sliced longitudinally. In (a): control group - sarcomere clearly delimited by the z lines (star), normal aspect of mitochondria (m) and paranucleate granules (arrows) with electron dark appearance were observed. In (b): electrical discharge group - note the high number of dropsy damaged mitochondria, disarranged sarcomere (star) and dispersed electrondense granules presence (arrows). In (c): post-discharge group - preserved mitochondria and electrondense granules dispersion tendency at the paranucleate region were verified seven days later to electrical discharges. Tangential cardiomyocyte image is visible (star). Amplification × 13.200.