[Reduction of dislocation of transvenous pacemaker electrodes taking intracardiac ECG potentials into account...

For the assessment of stable positions of the electrodes radiographic control, threshold measurements and methods provoking dislocation are used. There is an average dislocation rate of endocardial electrodes of 7-11%. As a further parameter for intra-operative assessment of a stable electrode position intracardiac R-potentials were measured with the stimulation electrode. While QRS complexes in the surface ECG remain unchanged, intracardiac electrocardiograms show an alternating height of the R-amplitude from one ventricular action to the next. From these differences (deltaR) a stable electrode position can be assumed as long as deltaR is small (our patient group 2.12mV+/-1.05MV). Large differences (6.9mV+/-1.7MV) indicate a non-optimal fixation of the electrode tip. The dislocation rate including the post-operative exit block could be reduced below 2% by consideration of the R-amplitude alterations.