Abstract
The performance of endocardial ventricular pacing was evaluated in 453 patients. The mean follow-up period was 59.8 months (ranging from 1 to 305 months). Acute pacing parameters such as stimulation threshold, lead impedance, and R wave amplitude were satisfactory in all patients except one with an extremely high pacing threshold. No significant differences were noted between steroid-eluting electrodes and non-eluting ones in their acute pacing parameters. Pulse width thresholds at 3.5 volts in the subacute phase (1 week after implantation) were also acceptable. These thresholds were statistically lower in steroid-eluting electrodes than in non-eluting ones.
Strength-duration curves (S-D curves) were measured at the times of both lead implantation and replacement of the pulse generator in 104 patients. Although chronic S-D curves were shifted upward and to the right, chronaxie did not change.
Some complications in pacing leads were recognized during the follow-up periods. Lead conductor fracture occurred in 15 leads, but the fracture sites were various. Lead tip dislodgement occurred in 4 leads (all de-tined type), 3 of which occurred within 24 hours, and in the remaining case, it occurred on the 24th postoperative day. Early battery depletion was recognized in 6 patients, 4 of whom showed marked elevation of stimulation threshold.
The overall performance in endocardial ventricular pacing including lead system was almost satisfactory, and measurement of the S-D curve seems to be useful to set the appropriate output with safety margin in both the acute and chronic period.
