The third decade of cardiac pacing. Multiprogrammable pulse generators.

Cardiac pacing as a clinical discipline is now over 20 years old. The end of the first decade saw the development of the demand pacemaker, the first "intelligent" implantable prosthetic device. Further progress took place mostly in the latter half of the second decade, with the introduction of lithium power sources with greater longevity, miniaturisation of electronic circuits, overall improvement in design with the widespread use of hermetic encapsulation of power sources and components for greater protection, and the development of noninvasive programmability. As we begin the third decade of cardiac pacing, the inexorable and accelerated growth of pacemaker technology has already fostered a large array of sophisticated multiprogrammable pulse generators, with a variety of functions. The complexity of pulse generators will inevitably continue to increase with the promise that devices will be far more specific in their clinical applicability. In 1978, about 36 per cent of all pacemaker implants in the United States used programmable pulse generators' and it appears almost certain that these units will largely or indeed completely replace non-programmable systems in the next few years as confidence and reliability improve and the benefits of non-invasive programming become more widely appreciated. Indeed, the greater longevity of lithium powered pulse generators can in itself be considered an important reason for programmability. It is impossible to predict in advance who will require modification of pacemaker variables and the likelihood of a change in a patient's requirements will undoubtedly increase the longer the same generator remains implanted.