Four years experience of cardiac pacemaking with the Devices asynchronous generator.

The results offixed-rate cardiac pacing during a 4-year period are reported. In go patients, I07 Devices TF (type 2970) asynchronous generators were implanted. An actuarial estimate ofgenerator lifetime showed that 84 per cent of generators were functioning at 2 years and 65 per cent at 3 years after implantation. Ten generators failed from battery depletion after more than 30 months' use, while generator malfunction was demonstrated in 9 of io unitsfailing before 30 months. At 2 years, 59 per cent ofpacing systems were satisfac- tory and 34 per cent continued in use for more than 3 years. Extrusion of the generator, exit-block, andfrac- tured electrodes accountedfor more than half the premature pacing system failures. Nine patients died during the period of study, none due to pacemaker failure. While pacemaker follow-up was minimal, only i6 6 per cent of generators were removed because of unpredicted failure. These results indicate that, with a reliable generator, pacemakerfollow-up can be simplified and this may encourage wider use of long-term pacingfor the management of heart block outside specialist centres.