Safety of Magnetic Resonance Imaging in Patients With Pacemakers and Defibrillators

Pacemakers and ICD's have traditionally been accepted as contraindications to MRI due to safety concerns. Recent work in our laboratory as well as our pilot study of approximately 500 patients has shown the safety of most contemporary implanted rhythm management devices in the MRI environment given appropriate precautions. Because the investigators have completed testing in animals weighing as little as 80 lbs. without incident, the investigators feel they can safely image children at this weight or greater (Circulation 2004; 110:475-482). The goal of this study is to expand on our pilot study and to develop a protocol, consistent with the Department of Health and Human Services (DHHS) requirements, that will increase our safety experience with clinically indicated MR imaging in patients with implanted cardiac pacemakers and ICD's. This is a cohort study. One thousand seven hundred patients with a clinical need for MRI will be recruited. Risks and Benefits associated with Magnetic Resonance (MR) imaging in the setting of implantable devices will be discussed and informed consent obtained. The type of device and leads will be ascertained. Patients will be monitored by a physician or a Registered Nurse (RN) with ACLS certification and familiarity with ICD/Pacemaker programming during the study. When imaging children who meet age and weight criteria, a physician will be present during the entire study. Fellow and attending radiology and electrophysiology support will be available in house in all cases. Standard device testing including battery voltages, thresholds, sensing and lead impedances will be measured.