Magnetic resonance imaging (MRI) is an essential medical imaging tool and has become the gold standard for imaging soft tissues structures. The number of patients with indications for pacemakers or implantable cardioverter-defibrillators (ICD) is increasing. However, both pacemaker and ICD systems are subject to several potential hazards secondary to the radiofrequency and magnetic fields created by MR. These potential hazards include movement and torque, electrical current induction with consequent myocardial capture and tissue injury reflected by increased capture threshold. Electromagnetic interference may also result in inhibition of pacing, inappropriate tracking, inappropriate ICD anti-tachycardia pacing and/or shocks, and alterations in programming.
According to presented at the European Congress of Radiology 2014 study patients implanted with a subcutaneous implantable cardioverter defibrillator (S-ICD System, Cameron Health and Boston Scientific) now can safely undergo MRI.
Since 2009, more than 450 patients around the world have been implanted with the S-ICD. The subcutaneous system does not require electrodes in or on the heart. The principle of this defibrillator is that it’s positioned under the skin and nothing is touching the heart; from this perspective, it’s safer.
The implant procedure for an MRI-ICD is very similar to a traditional ICD implant. The device is placed under the skin, near the collarbone, and with the guidance of X-rays, wires are placed into blood vessels going into the heart. The entire procedure takes between one and two hours.
However, although MRI is safe in patients with S-ICD, “more work on the optimization of sequences for heart examination is needed.