LONG TERM PERFORMANCE OF CARBON-BRAIDED AND IRIDIUM OXIDE-COATED DEFIBRILLATOR LEADS IN PATIENTS WITH IMPLANTABLE DEFIBRILLATORS.
R.D.Wuttke* and J.T.Y.Hii.
Cardiology Unit, Queen Elizabeth Hospital, Adelaide, South Australia
Electrodes coated with iridium oxide (IROX) may produce lower pacing thresholds and impedance. In this study, we assessed the long term performance of the Intervene lead (Intermedics IROX lead) and the carbon braided ENDOTAK lead (CPI).
Methods:Lead performance was investigated in 14 patients (8 CPI, 6 IROX). Lead parameters were measured at implant, 3 weeks, 4 months and 10 months post implant. Threshold voltage, lead impedance and sensed R wave amplitude were measured in a supine position. Comparisons were made within each lead as well as between leads at different time points.
Results: At10 month follow-up, both leads showed a significant increase in pacing threshold from implant value - CPI 0.5±0.2V to 1.8±1.4V(p=0.02) and IROX 0.4±0.1V to 1.1±0.2V(p=0.0005). There was no significant difference in pacing thresholds between leads at each time point. Regression analysis of serial impedance measurements showed no significant time dependent change. However this analysis showed a significantly lower impedance in the IROX lead (y intercept 539±82W vs 401±65W, p<0.005). For the IROX lead, sensed R wave amplitude significantly increased up to 4 months post implant (15.2±7.7mV to 20.7±6.7mV, p=0.02). There was no significant change in R wave amplitude with the CPI lead.
Conclusions:Both leads show a time dependent increase in pacing threshold but without significant difference between them. The IROX lead exhibited a 25% lower impedance. Sensed R wave amplitude continue to increase post implant with the IROX lead. However, both leads show satisfactory R wave sensing.
