THE PATIENT ALERT SYSTEM - PILOT-STUDY OF BUILT-IN WARNING SYSTEMS FOR PACEMAKERS

Malfunction of a pacing system can be life-threatening for a pacemaker -dependent patient. It would be desirable for implantable pulse genera tors to have a built-in automatic warning system capable of alerting t he patient as soon as a potentially dangerous disorder is defected In this study, seven patients (mean age, 72.6 +/- 10.7 years) with slow, chronic atrial fibrillation underwent implantation of a dual-chamber p ulse generator with a custom-made ''alert electrode'' connected to the atrial port of the pulse generator to stimulate the underlying pector al muscle. The muscle was temporarily stimulated while the pacemaker w as in VVIR mode. The lowest amplitude sufficient to alert the patient (perception threshold) was 1.6 +/- 0.58 V at 0.45 ms during implantati on and 1.2 +/- 0.5 V at 0.45 ms chronically. In a second phase, alerts outside of the office were issued using a special software routine ca pable of delivering stimuli at programmable date and time.