INTERINDIVIDUAL VARIABILITY OF PACING IMP EDANCE DURING FOLLOW-UP

As pacing impedance is inversely related to pacing current, the increa se of pacing impedance additionally decreases pacing current. Whether the impedance measurement at implantation predicts the outcome during follow-up, was studied in 87 patients who received the VDD-single lead UniPass 425 connected to the pacemaker Unity (Sulzer Intermedics). Th e impedance changes between implantation and 6 months follow-up were a ssessed for each patient. Similar impedance values were defined, if th e two measurements were within a range less than or equal to -100 to 100 Ohm. Six-months impedance was lower or higher compared to implanta tion, if the difference exceeded > -100 or > +100 Ohm. At implantation , impedance was 535 +/- 98 Ohm (range: 333-811 Ohm) and significantly increased to 604 +/- 160 Ohm (range: 361-1150 Ohm) after 6 months. Mea n difference between the two measurements was 69 +/- 162 Ohm (range: - 336 bis +560 Ohm). Similar impedance had 43 (implantation: 527 +/- 75 Ohm, 6 months: 531 +/- 87 Ohm), lower values II (implantation: 660 +/- 83 Ohm, 6 months: 494 +/- 73 Ohm) and higher values 33 patients (impl antation: 503 +/- 99 Ohm, 6 months: 735 +/- 168 Ohm). Compared to the patients with similar impedance patients with lower impedance had a si gnificantly higher impedance values at implantation. Conclusions: Paci ng impedance increased significantly within 6 months after implantatio n. Pacing impedance changed > 100 Ohm in 51 % of the patients. The lon g-term follow-up of pacing impedance can be predicted generally, but n ot for the individual patient.