Since their early invention, pacemakers have reached a considerable level of technological progress and a myriad of clinical indications. However, they have a reported complication rate of 1¿6%. This obligates every emergency room physician to know and understand the basis of pacing and to be familiarized with the most common complications. Moreover, a fast and precise diagnosis has a considerable impact on mortality and morbidity. Hence, this chapter focuses on the most common pacemaker complications that could present to the emergency room. These emergencies can be divided into mechanical and electrical and range from mild to fatal. By including the most recent information from guidelines, reviews, and case studies, this chapter will give the emergency room physician a quick review of the complications, clinical diagnostic keys, high-clinical suspicion signs, and possible treatments. Additionally, a brief section about the basis of pacing is included. Other cardiac devices, such as defibrillators and cardiac resynchronization therapy, are out of the scope of this chapter and will just be briefly commented.
