RESUMO
BACKGROUND AND OBJECTIVES: It has been suggested that lead impedance measurements with using real-time telemetry may offer a good estimation of the lead system integrity, and the serial measurement of the pacing lead impedance over time is a useful tool to monitor the pacing lead performance. However, there has been no consistent data about the changes of lead impedance over time. Therefore, we investigated the correlation of the direct lead impedance and the telemetered lead impedance, and the changes of lead impedance over time in both the atrial and ventricular leads. SUBJECTS AND METHODS: The direct and telemetered lead impedances were measured at the time of the initial implantation. One-hundred and five patients (mean age: 62.5+/-13.5 years, 47 males, 47 atrial leads and 105 ventricular leads) who were without lead failure for more than 4 years since the initial implantation were included in the study. Afterwards, the telemetered lead impedance was examined at 2-month and at 12-month after implantation and then annually for 4 years in all the patients at a pacemaker clinic. RESULTS: At the initial implantation, the direct lead impedance and the telemetered lead impedance were 470.2+/-12.2omega and 540.9+/-11.6omega, respectively, in the atrial leads (r=0.72, p<0.01) and 623.7+/-14.6omega and 717.1+/-17.3omega, respectively, in the ventricular leads (r=0.82, p<0.01). In the atrial leads, the mean telemetered lead impedance rose to 583.0+/-14.0omega (p<0.01 vs baseline) at 2 months and it stabilized thereafter (p=NS). In contrast, the mean lead impedance was decreased to 653.6+/-15.6omega (p<0.01 vs baseline) at the 2-month follow-up, and then it stabilized in the ventricular leads (p=NS). CONCLUSION: There was a good correlation between the direct and telemetered lead impedance, and there was a different tendency for the change of lead impedance during the lead maturation between the atrial and ventricular leads. The telemetered lead impedance was substantially stable since the 2 months after the implantation.