Abstract
Since 1972, 499 pacemakers had been implanted in 374 patients. 457 endocardial leads and 18 myocardial leads were inserted. Ten lead fractures (2.1%, 20 insulation failures (4.2% and 5 elevations of pacing threshold (1.1%) occured in our cases. Those were studied and evaluated in this report. The lead fractures were observed most often at the extravascular segment of the leads, which were bended strongly, 5 cases(50%, and next most frequently at the fixation of the leads. Scanning electron microscopes (SEM) found that the lead fractures at the bended segment were induced by the fatigue breakdown. Eighty-eight % of insulation failure occured at the segment of leads contacting with the generator, SEM found that thinness of insulated silicone induced to the failure. Elevation of pacing threshold occured in one patient at 30 months post operatively, in which the tip of second lead was inserted near the previous one in the right ventricle. Elevation of pacing threshold occurred also in another 4 leads over 8 years. We conclude that the present pacemaker leads are satisfactory enough to be used in long term basis when we consider proper oparative prosedure and lead selection.
