Electrophysiologic monitoring required during MRI due to changes in device variables, programming
TUESDAY, Oct. 4 (HealthDay News) -- Magnetic resonance imaging (MRI) can be performed safely in certain patients with implanted cardiac devices by using a protocol based on device selection and programming, along with proper electrophysiologic back-up support, according to a study published in the Oct. 4 issue of the Annals of Internal Medicine.
Saman Nazarian, M.D., from Johns Hopkins Hospital in Baltimore, and colleagues examined the safety of a protocol for MRI of magnetic strength 1.5 Tesla in patients with implanted cardiac devices. A total of 438 patients with pacemakers and defibrillators (54 and 46 percent, respectively) who underwent 555 MRI studies were monitored by a trained nurse for blood pressure, electrocardiography, oximetry, and symptoms, with immediate back-up available from an electrophysiologist. Pacing mode was changed to asynchronous and demand for pacemaker-dependent patients and others, respectively. The activation or inhibition of pacing, symptoms, and device variables were measured.
The investigators found that the device reverted to a transient back-up programming mode without long-term effects in 0.7 percent of the patients. Post-MRI, there was an immediate reduction in right ventricular (RV) sensing, and atrial and right and left ventricular lead impedances. Long-term follow-up showed decreased RV sensing and lead impedance, increased RV capture, and decreased battery voltage. No device revision or reprogramming was required for the observed changes.
"With appropriate precautions, MRI can be done safely in patients with selected cardiac devices. Because changes in device variables and programming may occur, electrophysiologic monitoring during MRI is essential," the authors write.
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