Extra-cardiac stimulators: what do cardiologists need to know?

For several decades, treating patients with pacemakers has been the privilege of cardiologists. However, in the last 30 years, researchers have found new targets for electrical stimulation in different clinical subspecialities, such as deep brain stimulation (for the treatment of Parkinson's disease, essential tremor, dystonia, and some psychiatric illnesses); spinal cord stimulation (for refractory angina, chronic pain, and peripheral artery disease); and sacral (for diverse urologic and proctologic conditions), vagal (for epilepsy), and phrenic nerve stimulation (for sleep apnoea). The purpose of this article is to familiarize cardiologists with these 'extra-cardiac pacemakers' and to discuss potential issues that must be addressed when these patients undergo cardiac procedures.