Format

Send to:

Choose Destination
See comment in PubMed Commons below
Ann Intern Med. 2011 Oct 4;155(7):415-24. doi: 10.7326/0003-4819-155-7-201110040-00004.

A prospective evaluation of a protocol for magnetic resonance imaging of patients with implanted cardiac devices.

Author information

  • 1Johns Hopkins University, Baltimore, Maryland 21287, USA. snazarian@jhmi.edu

Abstract

BACKGROUND:

Magnetic resonance imaging (MRI) is avoided in most patients with implanted cardiac devices because of safety concerns.

OBJECTIVE:

To define the safety of a protocol for MRI at the commonly used magnetic strength of 1.5 T in patients with implanted cardiac devices.

DESIGN:

Prospective nonrandomized trial. (ClinicalTrials.gov registration number: NCT01130896) SETTING: One center in the United States (94% of examinations) and one in Israel.

PATIENTS:

438 patients with devices (54% with pacemakers and 46% with defibrillators) who underwent 555 MRI studies.

INTERVENTION:

Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Tachyarrhythmia functions were disabled. Blood pressure, electrocardiography, oximetry, and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had immediate backup from an electrophysiologist.

MEASUREMENTS:

Activation or inhibition of pacing, symptoms, and device variables.

RESULTS:

In 3 patients (0.7% [95% CI, 0% to 1.5%]), the device reverted to a transient back-up programming mode without long-term effects. Right ventricular (RV) sensing (median change, 0 mV [interquartile range {IQR}, -0.7 to 0 V]) and atrial and right and left ventricular lead impedances (median change, -2 Ω [IQR, -13 to 0 Ω], -4 Ω [IQR, -16 to 0 Ω], and -11 Ω [IQR, -40 to 0 Ω], respectively) were reduced immediately after MRI. At long-term follow-up (61% of patients), decreased RV sensing (median, 0 mV, [IQR, -1.1 to 0.3 mV]), decreased RV lead impedance (median, -3 Ω, [IQR, -29 to 15 Ω]), increased RV capture threshold (median, 0 V, IQR, [0 to 0.2 Ω]), and decreased battery voltage (median, -0.01 V, IQR, -0.04 to 0 V) were noted. The observed changes did not require device revision or reprogramming.

LIMITATIONS:

Not all available cardiac devices have been tested. Long-term in-person or telephone follow-up was unavailable in 43 patients (10%), and some data were missing. Those with missing long-term capture threshold data had higher baseline right atrial and right ventricular capture thresholds and were more likely to have undergone thoracic imaging. Defibrillation threshold testing and random assignment to a control group were not performed.

CONCLUSION:

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.

PMID:
21969340
[PubMed - indexed for MEDLINE]
PMCID:
PMC4337840
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Silverchair Information Systems Icon for PubMed Central
    Loading ...
    Write to the Help Desk