Preclinical evaluation of implantable cardioverter-defibrillator developed for magnetic resonance imaging use.
BACKGROUND
Many patients with an implantable cardioverter-defibrillator (ICD) have indications for magnetic resonance imaging (MRI). However, MRI is generally contraindicated in ICD patients because of potential risks from hazardous interactions between the MRI and ICD system.


OBJECTIVE
The purpose of this study was to use preclinical computer modeling, animal studies, and bench and scanner testing to demonstrate the safety of an ICD system developed for 1.5-T whole-body MRI.


METHODS
MRI hazards were assessed and mitigated using multiple approaches: design decisions to increase safety and reliability, modeling and simulation to quantify clinical MRI exposure levels, animal studies to quantify the physiologic effects of MRI exposure, and bench testing to evaluate safety margin.


RESULTS
Modeling estimated the incidence of a chronic change in pacing capture threshold >0.5 V and 1.0 V to be less than 1 in 160,000 and less than 1 in 1,000,000 cases, respectively. Modeling also estimated the incidence of unintended cardiac stimulation to occur in less than 1 in 1,000,000 cases. Animal studies demonstrated no delay in ventricular fibrillation detection and no reduction in ventricular fibrillation amplitude at clinical MRI exposure levels, even with multiple exposures. Bench and scanner testing demonstrated performance and safety against all other MRI-induced hazards.


CONCLUSION
A preclinical strategy that includes comprehensive computer modeling, animal studies, and bench and scanner testing predicts that an ICD system developed for the magnetic resonance environment is safe and poses very low risks when exposed to 1.5-T normal operating mode whole-body MRI.
['Gold|Michael R|MR|', 'Kanal|Emanuel|E|', 'Schwitter|Juerg|J|', 'Sommer|Torsten|T|', 'Yoon|Hyun|H|', 'Ellingson|Michael|M|', 'Landborg|Lynn|L|', 'Bratten|Tara|T|']
D000818:Animals D002318:Cardiovascular Diseases D017147:Defibrillators, Implantable D004869:Equipment Safety D006801:Humans D008279:Magnetic Resonance Imaging D010138:Pacemaker, Artificial D015203:Reproducibility of Results D014693:Ventricular Fibrillation
Implantable cardioverter-defibrillator Magnetic resonance imaging Hazards Ventricular fibrillation detection Defibrillator Lead electrode heating