The value of an oscilloscope in routine checking of pacemakers

An evaluation has been made of the usefulness of the oscilloscope at routine check-ups of cardiac pacemakers. Measurements of 100 consecutive implanted pacemakers, obtained after their removal have been compared with changes in rate and changes in impulse duration and amplitude obtained at previous routine controls. Other changes in pacemaker characteristics have also been evaluated. Eight faulty pacemakers were found. Six had a decreased voltage, none however, less than 3.5 volts. Five of them had shown a decrease in rate by at least 7 impulses per minute, while in one QRS-synchronized pacemaker the synchronizing circuit did not function. In one pacemaker the stimulating rate had increased with 20 impulses while in one P-synchronized pacemaker the delay time had decreased. In 6 patients a significant decrease of the impulse amplitude was noticed without fall in voltage or electronic failure and in 3 others no decrease of the impulse duration was noticed in spite of decreased voltage at check after explantation. The present study therefore indicates that, at routine check-ups of the presently analyzed pacemakers with voltage depending stimulation rate, an analysis of the latter gives satisfactory information of pacemaker function and can be used instead of oscilloscope test, eventually in combination with electronic measurements of impulse duration.