Cardiac pacemakers. Principles and practices

The fact that prolonged electrical treatment for complete heart block and other arrhythmias is possible cannot be disputed. There is, however, a continuing need to define the parameters of long-term stimulation in precise terms which include current, voltage, stimulus duration, electrode surface area, and a specific need to relate these to the levels and conditions where pacing can be hazardous. The electrodes for permanent pacing may, at the discretion of the surgeon, be placed at thoracotomy or passed transvenously. In the case of the latter a unipolar system utilizing a stainless steel or Elgiloy cathode and a monophasic wave form are preferred.Synchronous pacing, although it is based on an impressive body of experimental evidence and numerous clinical studies, has not yet been proved clearly beneficial. Demand or standby pacing is probably the most significant and promising of recent modifications. Paired and coupled pacing, although hazardous, may have increasing usefulness in certain acute situations. Future development may lead to refinements in hardware or possibly to a completely new approach to the treatment of ventricular arrhythmias.