Reliability of atrial screw-in leads.

The aim of this study was to investigate long-term performance of a carbon coated atrial screw-in lead. During implantation of 247 leads of this type we measured an average stimulation threshold of 0.74 (range: 0.2-1.6 V) at 1 ms pulse width. Mean lead impedance came to 446 ohms (range: 263-1000 ohms) resulting in an arithmetical energy consumption of 1.51 microJ (range: 0.1-7.21 microJ). Average P wave amplitude was 3.9 mV (range: 1.3-11 mV). After a mean follow-up of 16.4 months (range: 3-60 months) we found excellent threshold results in 76% of the patients permitting a safety programming at half of nominal value. An additional 14% nominal settings could be retained. With regard to chronic lead impedance of 488 ohms (range: 315-1327 ohms) we calculated an average chronic energy consumption of 10.83 microJ (range: 1.62-22.78 microJ) during safety programming. This made up 34.6% of the corresponding energy consumption during nominal programming. Eighty percent of the patients showed chronic P waves above 2 mV; nearly half of them (n = 94 = 38%) showed a proper sensing function even when programmed to minimal sensitivity settings or above 4 mV. In 19 leads (8%) we observed unsatisfying threshold results requiring high output programmings. All threshold increases occurred within the first year, 84% (n = 16/19) within the first 3 postoperative months. An additional five leads (2%) were found to have a loss of capture, and one (0.5%) a loss of sensing.(ABSTRACT TRUNCATED AT 250 WORDS)