Wearers of implanted cardiac devices such as pacemakers (pictured) and defibrillators can safely undergo Magnetic Resonance Imaging (MRI) scans, according to a report by cardiologists at Johns Hopkins Hospital, USA.
The report outlined a protocol for safe MRI scans based on device selection, programming and careful patient monitoring.
MRI scans, which are important for the diagnosis and monitoring of tumours and other soft tissue pathologies, have traditionally been considered too dangerous for people with implanted devices.
Saman Nazarian, cardiac electrophysiologist, said: “The guidelines we have published can be used to make MRI more available to people who could benefit from early detection of cancer and other diseases and for guiding surgeons during procedures.”
The study followed 438 people with implanted cardiac devices. With appropriate precautions, the researchers found, patients with pacemakers and defibrillators can undergo an MRI scan with very low risk of the device malfunctioning, moving or heating.
The protocol, developed over 15 years by cardiac electrophysiologist and biomedical engineer Henry Halperin, includes:
- Checking the age of the device – pacemakers made after 1998 and defibrillators made after 2000 have electromagnetic interference protection.
- Checking the type and configuration of the leads – e.g. if a lead is disconnected and not part of the device’s function, an MRI is not safe.
- Reprogramming the device to a safe mode during the scan.
- Monitoring the patient’s blood pressure, oxygen saturation and electrical activity of the heart, and looking for any unusual symptoms.
- Checking and reprogramming the device after the scan.
- A follow-up check after 3–6 months.
“With the advancing age of the population and the expanding indications for pacemakers and defibrillators, this has become an increasingly important issue, and a lifesaving one for some patients,” commented Nazarian.