[Stress tolerance of various catheters in the electrical interruption of AV conduction]

To date, only commercially available cardioverters and standard electrode catheters have been used for closed-chest ablation of the atrioventricular conduction system; the latter are primarily designed for temporary pacing and electrophysiological examinations, both procedures requiring rather low voltages and currents. Therefore, the purpose of this experimental study was to assess the electrical charge when using high energies, for instance of 400 joules. A total of 7 different catheters with 2-4 electrodes produced by various manufacturers were tested. After discharging the capacitor (400 joules; commercially available cardioversion unit) the voltage and current were measured using an oscilloscope and the electrical flash was photographed. For temporary pacing previously used and newly sterilized catheters of varying sizes and numbers of electrodes tolerated only one single charge of 400 joules, a completely new catheter only a maximum of 3 discharges. Any additional test resulted in a non directional discharge, caused by an insulation defect. A Josephson catheter (USCI) and a newly developed catheter with modified insulation and electrode material (Cordis) had a higher stability. Both tolerated at least 5 charges per electrode, and in addition the Cordis probe tolerated another 20 charges of the 2nd lead without any non directional discharges. Thus, commercially available electrode catheters are of limited electrical stability when used for closed-chest ablation of the atrioventricular conduction system. For the protection of the patient and to prevent therapeutic failure, a maximum of 3 electrical discharges are possible when using a completely new catheter. As modified catheters demonstrate (currently only available in prototype), the electrical quality could be improved.(ABSTRACT TRUNCATED AT 250 WORDS)