What theoretical effect poses a threat to a patient with a heart valve containing non-magnetic metallic disks?

The theoretical effect that poses a threat to a patient with a heart valve containing non-magnetic metallic disks is Lenz's effect. This phenomenon occurs when a changing magnetic field induces an electric current in a conductor, which can lead to a corresponding magnetic field that opposes the original change. In the context of an MRI environment, the strong and rapidly changing magnetic fields can generate eddy currents in metallic objects, such as the non-magnetic metallic disks in a heart valve.

When these currents are induced, they can create forces that may affect the stability and position of the metallic components within the body. This effect is particularly concerning in a clinical setting, as it can lead to unintended movement or heating of the device, potentially causing harm to the patient. Understanding Lenz's effect is crucial for assessing safety in patients with implanted metallic devices during MRI scans.