Three-Dimensional Electrocardiography of Cardiac Pacing

Electrocardiographic evaluation of modern pacing systems requires sustained documentation during iterative programming procedures, exercise testing or Holter monitoring. Documentation of a prolonged period of time in standard electrocardiography is based on horizontal compression. The value and limitations of a vertical compression with no change in horizontal chronology and waveform morphology are evaluated. The signal taken from a selected surface lead is introduced into an oscilloscope triggered by an electrocardiographic event along the horizontal axis. A continuous vertical monitoring provides a vertical superimposition of the consecutive cycles. The brightness is proportional to the amplitude of the signal and introduces a third dimension. The three-dimensional technique results in an original image allowing report miniaturization at standard 25 or 50 mm/sec paper speed. Appropriate lead selection and use of the brightness as a marker event allow reliable atrial activity identification. In rate responsive pacing evaluation, the procedure is specifically convenient to full disclosure of the chronotropic response. The main limitation is a high sensitivity to noise during recording. Further developments are to be expected based on computer-assisted electrocardiography.