[Effects of the electric current on the fundamental processes of stimulation in the heart]

On the basis of experimental studies on isolated preparations from different regions of the heart and on perfused hearts of animals, it was possible to distinguish at least four basic actions of an electric current: 1. the release of excitations, 2. with continuous current, an electro-tonic influence on the pacemaker activity in the sense of a cathodic advancement, or an anodic inhibition 3. with alternating current, stimulation of the vegetative nerves of the heart, 4. a direct, reversible damage of the membrane by the current. Depending on the conditions of the action of the current (nature of current, current density, period of action, moment of start of action, etc.) the basic actions can lead to difference influencing of the heart functioning. Excitation, occurrence of fibrillation and defibrillation are due to stimulation. Heart stoppage may be the expression of vagus stimulation or a direct damage to the membrane. The occurrence of these effects is discussed for each case.