Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

Abstract

Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With 'MR-conditional' devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers.

Keywords: Cardiac pacemaker; Cardiovascular magnetic resonance imaging; ICD; Implantable cardioverter defibrillator; MRI conditional devices; MRI safety.

Figure 1.

Two representative intracardiac electrogram readouts from conventional implantable cardioverter defibrillators during magnetic resonance imaging. Note pacing inhibition and VT detection due to radio frequency noise after starting magnetic resonance imaging. Potential incidence of accordant effects is dependent on many factors such as device, device programming, scanner, and pulse sequence characteristics.

Figure 2.

Visualization of pacemaker heating due to radio frequency pulses in magnetic resonance imaging. (A) Experimental setup emulating left thoracic implantation of a conventional one-chamber pacemaker system in a gel-filled torso phantom. Arrows indicate pacemaker lead. The (black) temperature probe is attached to the tip of the pacemaker lead. (B) Heat map assessed by an infrared camera after 2 min of magnetic resonance imaging using a turbo spin echo sequence indicates the temperature increase at the lead tip.

Figure 3.

Representative magnetic resonance imaging artefacts in patients with a left thoracic cardiovascular implanted electronic device. (A) Four-chamber view. (B) Short-axis view. Image distortion/void hampering diagnostic image quality particularly regarding the right ventricle and anterior wall of the left ventricle is apparent. RV, right ventricle; LV, left ventricle.