[Damages of malfunction of the electrostimulating system (author's transl)]

In this study we describe the damages, or the ill-functioning of the electrostimulating system due to failure or bad functioning of the catheter electrode, of the electronic circuits and of the energy sources. Complications due to iatrogen causes or to clinical pathology have not been dealt with. Defects of electrostimulation are described in their clinical, electrocardiographic, oscilloscopic and electrophysiologic aspects, and in the operative report, through the study of 1455 cases. In the differential diagnosis of the defects of electrostimulation we point out their biological causes. The sheath interruption, observed in 31 cases, causes defects in electrostimulation, depending on the extension and on the position of the unsheathing. The circuit variations can be compared with the effect produced by a shunt capacitor. The sheath interruption causes a current reduction which reaches stimulating surface and the differential diagnosis concerns the electronic failure of the generator, the battery discharge, the organic liquid infiltration in the insertion point, the position of the catheter, and the tip perforation of it. The breaking of the spiral (in 6 cases) can be partial or total, and may be compared to the forming of a series capacitor between the electrodes which may sham the increase of the myocardic threshold. The stimulating surface, too wide respecting the intensity supplied by the electrostimulator, brings about a low current density and failures in electrostimulation; the difference between such condition and the one caused by a high myocardiac threshold is shown by determining the safety factor. A very small stimulating surface increases the electrode impedance and may cause a defect of the perception function, if the generator input impedance (4 cases) is reduced. The fall of the output voltage may be caused by a battery discharge, and is the most frequent cause of electrostimulation disturbances; it has been observed in 432 cases. Other causes of the fall of the output voltage (30 cases) are the outflow of mercury from the cells, or mycotic formations. The ill-functionning or the loss of perception (9 cases) caused by defects of the electrostimulator must be distinguished from the ones caused by the endocavitarian potential reduction (myocardiac infarction, conduction disturbances: 2 cases). Variations of the stimulating cycle can be caused by ageing, humidity on resistances and on oscillator condensers (9 cases). Accelerated stimulating was observed in 1 case, plate corrosion in 3 cases, high density of anodic current in 9 cases, generator turnover in 3 cases. Finally we give the chief points of electrical stimulating disturbances due to interferences of electromagnetic radiation.