Runaway pacemaker. Unpredictable pacemaker failure.

The runaway pacemaker is an uncommon but very serious complication of permanent artificial pacemakers. Although the runaway pacemaker has been most frequently encountered in older (fixed rate) pacemakers, this problem has also been reported in various types of newer models manufactured by different companies. The most striking finding in our case is that the pacemaker was reported by a reliable pacemaker follow-up service to be working normally only one week before the development of the malfunction. The extremely rapid pacing rate (750 beats per minute) was a manifestation of a far-advanced runaway pacemaker. The manufacturer believes that this is the first reported incident of a runaway pacemaker in this model. This indicates that the runaway pacemaker is still a potential problem, even in newer pacemakers, and reemphasizes the unpredictable and serious nature of this medical emergency.