[Cellular electrophysiological and histopathological study of the effects of continuous electric current on the sheep heart].

The energy released in electrode catheter ablation is spent on thermal, mechanical and electrical effects. The relative importance of these effects and their role in the adverse reactions of the method are controversial. Low-energy shocks have been shown to modify cellular electrophysiological and histopathological parameters in the sheep heart. The purpose of this study was to individualized the effects of the electric current itself, using an isolated electrode to suppress barotrauma and reduce the amount of energy delivered. Three fragments of epicardium, seven false tendons and eight loop-shaped strips were placed in an electrophysiology bath perfused with Tyrode's solution and subjected to an electric field induced by an 18 V battery without discharge from a condenser, so that all mechanical effects were suppressed. The electric field was supplied via an isolated electrode, thus preventing the current from leaking through the Tyrode's solution and forcing it across the fragments studied. The electrophysiological parameters were studied by the microelectrode method on both sides of the area subjected to the electric field. This was followed by a histological study. The current intensity was 15 mAmp, and the energy delivered in one second was 270 mJ. Membrane depolarization was constant, and no automatic of post-depolarization activity was observed after the electric current was applied. The two-dimensional conduction accounted for the absence of block in the epicardial fragments. In the false tendons a conduction block constantly appeared between the two electrodes, associated with a decrease in conduction velocity in the recovery phase (2.1 +/- 0.24 vs 1.8 +/- 0.23 m/s, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)