A new method of single-lead DDD stimulation

Many efforts have been made to develop a single-lead DDD stimulation. Recently a new method for this pacing mode was empirically developed by means of animal experiments. This mode uses a three electrode configuration consisting of two floating electrodes in the atrium and the pacemaker connected to ground for releasing two overlapping oppositely polarized pulses from the floating electrodes. These experiments resulted in very low atrial threshold voltages from 1 to 2 Volts. In this study, the physical background of this new pacing mode is investigated by means of in vitro electrical field measurements. Following this investigations the low threshold voltages are due to a distorted and locally increased electrical field in the upper part of the atrium compared to the usual bipolar stimulation. Following this an implantable pacing system was developed and the new pacing mode evaluated. The first pacemaker was implanted and low threshold voltages were measured for the single-lead DDD mode