People with pacemakers and implantable cardioverter-defibrillators (ICDs) are usually told that they can’t get an MRI scan. The worry being that the powerful magnetic fields and radio waves used in the MRI scanners might fry the devices, induce a current in the pacemaker making the heart beat wildly or, in the case of ICDs, cause an unnecessary shock.
Dr. Naveen Bhamri says, MRIs can be done safely if pacemakers and ICDs are temporarily reprogrammed so they don’t react to an MRI’s magnetic field.
The answer to this question is not a simple yes or no, it depends on the type of device you have.
What about CT Scans?
A CT (computed tomography) Scan generates a cross-sectional view of your body through a series of X-ray images. If you have any device implanted in your chest or body, it’s safe for you to have a CT scan. There are no limitations. Although the scan will not affect your device, if it is on the larger side, your device can sometimes affect image quality.
Some of the larger devices like left ventricular assist devices, some defibrillators and pacemaker can create dense streaks that partially obscure the images we acquire with the CT scan. But that would not prevent people from doing a CT scan.
What about MRI exams?
MRI (magnetic resonance imaging) uses a large, circular magnet and radio waves to produce clear computer images of the body. Most heart valves and coronary artery stents currently on the market that is implanted in patients can go safely through an MRI scanner. Earlier, the healthcare industry considered it unsafe for patients with pacemakers and defibrillators to go into an MRI scanner. However, manufacturers have developed some pacemakers and defibrillators that can be scanned with an MRI. They’re referred to as ‘MRI-conditional’. MRI scans can be performed on patients with these devices, though there are limitations.
What about Older Devices?
If it’s an older pacemaker that is not MRI-conditional, MRI scan is not recommended. During an MRI, electricity applied to the magnet creates an alternating magnetic field. If you placed a wire within that alternating magnetic field, it could generate current and heat up.
For pacemakers and defibrillators, metal “leads” that are similar to wires are implanted in the body and the heart muscle. Leads that come within the MRI scanner’s alternating magnetic field can generate electricity, or heat up while touching your heart.
The worry is that the heart muscle might get burned, which could potentially turn into scar tissue. Since a current is developed within the lead, the concern about stimulating the heart is that it’ll start beating abnormally and create an arrhythmia within the heart.
Is the risk of a problem absolutely zero? No. But it’s small enough so that if the proper precautions are taken it is reasonable to see the benefit of the MRI scans as outweighing the risks if you have an implanted device or pacemaker.