MRI scans used to look inside the human body can have potentially fatal side effects for patients with pacemakers and implantable heart defibrillators, a Harvard medical School publication reported.

The April issue of the Harvard Heart Letter said the strong magnetic field and radio wave pulses used by an MRI can alter the way these implantable devices manage heart rhythms. The news is troubling as MRIs can be lifesaving, helping to diagnosis all sorts of problems.

Among the potential problems, the MRI’s magnetic field could shake the heart device out of position. The magnetic field can also create an energy flow in the wire that connects the device to tissue, causing heating and scarring.

Additional concerns include electrical currents causing the devices to overly stimulate the heart, and unintentional reprogramming of the implants.

Currently, there are no federally approved pacemakers or defibrillators that have been built from the start to be completely MRI safe, the publication said. The publication added that there are no approved MRIs deemed safe for the devices either.

This incompatibility is proving to be a real concern, as it precludes many with implantable heart devices from taking advantage of the imaging technology. MRIs are increasingly being used as a diagnostic tool for such health issues as strokes and cancer.

To make the devices compatible, heart device manufactures would have to build devices that can tolerate an MRI’s energy forces.

One company looking to make biomedical devices compatible with MRIs is Biophan Technologies, which is traded on the bulletin boards. The West Henrietta, New York-based company is using technologies based on advances in nanotechnology and thin film coatings.

But Biophan, which has a market cap of about $129 million, is being helped in its efforts to make biomedical devices compatible with stent-maker Boston Scientific. The companies have a joint development and licensing agreement. Boston Scientific is also poised to become a leading defibrillator and pacemaker manufacturer, once its acquisition of Guidant closes, which is expected on Friday.

Biophan also holds joint development and licensing agreements with NASA’s AmesCenter for Nanotechnology.