Transesophageal cardiac pacing during magnetic resonance imaging: Feasibility and safety considerations

Abstract

The feasibility and safety of transesophageal cardiac pacing during clinical MRI at 1.5 Tesla is considered. An MRI compatible pace catheter was developed. In vitro testing showed a normal performance of the pulse generator, image artifacts that extended less than 11 mm from the catheter, and a less than 5% increase in noise. Cardiac stimulation induced by MRI was not observed and, theoretically, is not expected. Potentially, tissue around the catheter tip may become heated. This heating (delta tau) was monitored. Eight dogs were exposed to MRI during pacing. For low RF radiation exposure, a time-averaged squared B1 field below 0.08 p tau 2 (SAR < 0.03 W/kg), delta tau was below 1 degree C. For high RF radiation exposure, but at normal RF radiation specific absorption rate (0.4 W/kg) delta tau was 5 degrees C. Thus, transesophageal atrial pacing during MRI at low RF exposure seems to be possible to perform cardiac stress studies or to correct unstable heart rates.

Strategy for Safe Performance of Extrathoracic Magnetic Resonance Imaging at 1.5 Tesla in the Presence of Cardiac Pacemakers in Non–Pacemaker-Dependent Patients

“…Maximum RF-induced heating occurs at the electrode-tissue boundary; that is, the area of endocardium and myocardium close to the tip of the electrode has a potential risk of thermal injury, 15 which may result in deterioration of pacing thresholds and/or atrial or ventricular perforation. The extent of RF-related heating depends on the SAR 16,17 of the sequence used, the position of the pacemaker lead loop in the RF coil, the configuration of the lead, and the specific lead model.…”

Magnetic resonance safety update 2002: Implants and devices

“…Cardiac pacemakers present potential problems to patients undergoing MR procedures from several mechanisms, including: 1) movement of the pacemaker (implantable pulse generator and/or leads) due to the strong static magnetic field of the MR system; 2) MRIrelated heating of the pacemaker lead by the time-varying fields; 3) inhibition or modification of the function of the pacemaker by the electromagnetic fields used for MRI; and 4) inappropriate or rapid pacing due to pulsed gradient magnetic fields and/or pulsed radio frequency (RF) fields (i.e., electromagnetic interference) from the operating MR system (i.e., with the pacing lead acting as an antenna) (4,5,8,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60). These problems may result in serious injuries or lethal consequences for patients.…”

“…It is well known that implants that have electronically activated or electrically conductive components can locally increase these currents, and under certain operational conditions, excessive heating of biomedical devices may occur in association with MR procedures (4,5,8,53,(61)(62)(63)68,69). For example, exorbitant temperature elevations from MRI-related heating have been reported for cardiac pacemakers, neurostimulation systems indwelling catheters with metallic components (e.g., thermodilution catheters), guide wires, disconnected or broken-surface RF coils, and improperly used physiologic monitors resulting in first-, second-, or third-degree burns (3)(4)(5)8,59,68,75). Thus, thermal injury must be considered as a possible adverse outcome if RF power is transmitted in the direct vicinity of the implanted device or its attached components.…”

“…Thus, thermal injury must be considered as a possible adverse outcome if RF power is transmitted in the direct vicinity of the implanted device or its attached components. Of note, there is a tendency for excessive heating to occur in looped or coiled devices because electrical currents are easily induced in these shapes during MRI (4,5,8,52,53,59,(61)(62)(63)68,69).…”

Safety of Simultaneous Scalp or Intracranial EEG during MRI: A Review

“…The paramagnetic or ferromagnetic materials are attracted by the forces of the magnetic fields. Second, RF electromagnetic fields, that are produced by RF coils during the MR sequence, contains two components; one magnetic (B 1 ), and the second non-conservative electric component [20,51]. For a circularly polarized B 1 , the electrical component can be expressed as follows:…”