Effect of damped sine-wave shocks on catheter dielectric strength

This study evaluated the ability of 24 new standard tripolar and quadripolar U.S. Catheter Instruments catheters to withstand a single damped sinusoidal shock delivered by a standard defibrillator. The schema for energy delivery was meant to simulate possible clinical practices. Delivered peak voltage and current were measured during each shock. Each electrode was examined for pitting and changes in line resistance as a consequence of the shock. Electrode pitting occurred on all selected anodal poles. However, it also was found on "unsolicited" electrodes from 7 catheters, indicating that current had followed unanticipated routes. Electrode line resistance was unmeasurable in 6 of these 7 inappropriately pitted electrodes. Delivered peak voltage and postshock catheter dielectric strength depended on the manner of energy delivery. To simulate a posterior septal accessory pathway ablation procedure, a shock was delivered to 2 proximal (anodal) poles in 16 quadripolar catheters (8 received 200 J and 8 received 360 J). Delivered peak voltage was 3,125 +/- 362 V for the 200-J shock and 4,100 +/- 160 V for the 360-J shock. Postshock catheter dielectric strength for the 200- and 360-J shock was 1,425 +/- 826 V and 601 +/- 707 V, respectively. This was significantly lower than peak delivered voltage (p less than 0.001 for either energy). To simulate His bundle or ventricular tachycardia focus ablation, 8 tripolar catheters each received a single 200-J shock to the tip electrode. This resulted in a delivered peak voltage of 2,900 +/- 351 V, compared with a postshock dielectric strength of 1,325 +/- 1,320 V (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)