In general, MRI is contraindicated in patients with pacemaker but in selected patients, it can be performed with precaution.
What is MRI?
MRI (Magnetic Resonance Imaging) is a safe and painless test. It is generally indicated when a doctor needs to see something inside your body which is not evident by general examination or not seen in an X – Ray or CT scan. The MRI helps to see disorders of organs, bones and tissues inside the body. Cardiac MRI can be indicated in symptoms concerning heart disease such as shortness of breath, chest pain, palpitations, dizziness or syncope. It may also be to monitor existing heart condition such as valve problem or heart failure.
Why are precautions important while doing an MRI?
MRI is associated with strong magnetic field during the test. Hence, precautions are recommended for performing the test. Any artificial implants in the body is one of the major contraindication. Pregnancy, kidney problems, allergy to the dye are few other major contraindications where the test cannot be performed.
Artificial implants where the test cannot be performed are as below:
1. Pacemaker and defibrillators
2. Artificial heart valves
3. Aneurysm clips
4. Cochlear implants
5. Metallic implants and prosthesis
6. Vascular stent or stent graft
7. Dorsal column stimulators
Why is pacemaker contraindicated?
The pacemakers have metal leads which look like wires which are implanted in the body. Thus, when they come under the influence of MRI rays they can generate current in your heart. It can have fatal effects on the patient. The rays can damage the parts of the device or reduce the function of the pacemaker. It can also trigger the pace. Generating shocks is one of the most fatal effect on the patient. The magnetic field exerts mechanical disturbances on the device causing electrical malfunction or sound that the pacemaker can infer as cardiac activity leading to myocardial damage. It can also disturb the functioning of the MRI machine. Patients with pacemakers often diagnose late for cancer and neurological conditions due to contraindication for MRI.
Newer Pacemaker Advances
New advances in science have enabled pacemakers which are compatible with the MRI scans. They are metal free. The patient is constantly monitored for the vitals while the test is being performed. Cardiac rhythm has to be closely monitored while doing the MRI by a cardiac specialist. FDA has approved certain pacemakers which are MRI compatible. These MRI compatible pacemakers are non-magnetic. Hence, safe.
Precautions to undergo MRI for a patient with pacemaker
• Presence of a clinician or cardiologist
• Defibrillator should be available
• ECG and cardiac rhythm should be constantly monitored while the MRI is going on
• The pacemaker programming should be monitored before and after the MRI test
• The implant must be installed minimum 6 to 8 weeks before the MRI is done. This is to ascertain that the body has well adapted to the pacemaker
• MRI should be stopped immediately if any unseen circumstances occur
• MRI should be done in a setup where you have an ICU or any emergency cardiac care
• Patient should be well informed of the consequences and a written consent is must
- If you have an older version of the pacemaker, it does not make sense to change the pacemaker as it calls for another surgery which comes with its own set of risks and complications.
The pacemaker comes with a card for its information. Like the certificate you receive when you buy diamond or any gadget. You receive a card for the pacemaker device for its identification and features. It includes the manufacturer, model name and model number, a website, and a phone number to call with questions. So, this card is important to know whether your pacemaker is MRI conditional or NO.
And if you do not have the details of your pacemaker stay away from MRI.
CT Scan is an alternative investigation that you can undergo
MRI machine Advances
In recent advances, the newer MRI machines have been restructured and redesigned to incorporate leads that are less affected by the magnetic and radio waves reducing the heat generation. These machines should be less than 1.5 Tesla waves. They have also changed the material used in the switches which are more predictable in the field where these waves are generated. Thus, there are less chances of complications in a patient with pacemaker.