Abstract 19715: Automated External Defibrillation for the MRI Environment Enables Imaging and Interventions in Higher Risk Patients
Background: MRI Imaging or MRI-guided interventions of higher-risk patients requires detecting and treating acute cardiac events inside the MRI environment, since current practice of removing the patients from the MRI suite prior to treatment (CPR, defibrillation) significantly (5-10% increase/min) increases morality risk. We developed the means to detect and localize acute ischemia in the MRI using an MRI-compatible 12-lead ECG [1,2]. We then developed an MRI-compatible automated external defibrillator (AED) , by adding peripherals to a commercial Zoll Medical M-series AED, retaining its features and functionality. Defibrillation in the MRI environment (in-bore or on-table) may enable growth of diagnostic and therapeutic MRI procedures.
Objectives: Establish (a) safety of imaging subjects connected to the MRI-compatible AED and (b) efficacy of defibrillation in the MRI bore.
Methods: Experiments were performed in a 1.5T MRI. In N=2 volunteers and N=3 swine connected to the prototype system. We studied temperature increases during lengthy high Specific Absorption Rate (SAR) SSFP and TSE imaging. In N=3 swine, we induced ventricular fibrillation (VF) electrically, and then studied the success of defibrillation inside the MRI bore, as well as the body displacement induced by the defibrillation pulses.
Results: MRI induced-heating was <1.20C during the highest (4.3 Watt/kg) SAR sequences, meeting regulatory limits (Fig. 1). Defibrillation in the MRI was 100% successful. When defibrillation followed VF, swine motion was <10cm, whereas when defibrillation was performed without prior VF, swine motion was extensive, demonstrating that at ≤3T fields, motion due to defibrillation results from muscle contraction and not magnetic-field-related Lorentz forces, supporting theory predictions.
Conclusions: The 1.5 T MRI-compatible AED met regulatory limits and defibrillated successfully.
References:  Tse MRM ’13,  Zhang MRM ’15  Schmidt JCMR ‘16
Author Disclosures: E.J. Schmidt: Research Grant; Modest; Siemens Heathcare, St. Jude Medical, E-TROLZ. R.D. Watkins: None. M.M. Zviman: None. M.A. Guttman: None. W. Wang: None. H.H. Halperin: None.
- © 2016 by American Heart Association, Inc.