TUESDAY, Dec. 15, 2009 (HealthDay News) -- MRI scans can pose a serious risk to people with heart pacemakers, researchers warn.
U.S. Food and Drug Administration researchers exposed pacemakers to a simulated MRI magnetic field and then measured the electrical voltage produced at the tip of the pacemaker lead, where it would touch the interior of the patient's heart.
The exposure to MRI magnetic pulses caused certain pacemakers to deliver a drastically altered pulse and stimulate the heart inappropriately, which could have serious consequences for a patient, the study authors reported in the Dec. 14 edition of BioMedical Engineering OnLine.
"MRI systems emit several types of extremely intense magnetic fields and have caused injury to patients due to interactions with pacemakers," study author Howard Bassen said in a news release from the journal's publisher. "Cardiologists who choose to scan patients with cardiac pacemakers must assess the risks versus the benefits of the scan. This paper identifies one more risk."
About 40 million MRI scans are performed annually in the United States, where 10 million people have pacemakers.
Pacemaker and MRI manufacturers instruct physicians not to expose patients with pacemakers to MRI scans, which can disrupt a pacemaker's electronic system and burn heart tissue at the tip of the pacemaker lead.
But, despite these instructions, some cardiologists have developed special protocols that describe how to perform MRI scans on patients with pacemakers. Their belief is that the diagnostic benefits of MRI outweigh the pacemaker malfunction risks.
The American Heart Association outlines devices that may interfere with pacemakers.