Einstein (São Paulo) (Dec 2006)
Electrical transthoracic discharges in albine rats: ultrastructural changes in atrial myocardium
Abstract
Objective: Morphological myocardial tissue cytoarchitecture alterationsafter transthoracic countershocks were extensively studied. The aim ofthe present study was to evaluate the electrical discharge applicationeffects to the atrium subcellular level. Methods: An electrical cardioverterwas adapted to small rodent animals for this study. Electrical dischargeswere applied to the precordial region of 30 rats. Three groups with tenanimals each were randomly constituted. Animals were divided into acontrol group - animals that remained on resting period and wereafterwards sacrificed; an electrical discharge group - animals thatremained on resting period, followed by ten electrical discharges of 300mV and sacrificed; and an electrical post-discharge group - animals thatstayed on a resting period and received ten electrical discharges like theelectrical discharge group, but were sacrificed seven days subsequently.Liver, adrenal and left atrium tissue fragments of all groups were examined.Results: In the control and in the post-discharge groups a normal cellularstructure aspect with preserved architecture of cardiomyocytes andcontinuous sarcoplasmic membrane integrity were observed. However,cardiac muscle fibers with mitochondrial edema and lysis occurred inthe discharge group. In all experimental groups hepatic glycogen andadrenal lipids were not depleted. Conclusion: Results evidenced that thealarm reaction did not occur immediately after the countershocks althoughatrium myocardial ultrastructure presented severe injury signals. Thepresent investigation was helpful, since important information should beconsidered in clinical application field on myocardial protectionproceedings before and after application of transthoracic countershockdischarges.
