by Frederik Joelving, last updated: 30 August 2012NEW YORK (Reuters Health) - a small study adds to mounting evidence that MRI can be safe for people with cardiac pacemakers or implantable defibrillator.
Manufacturers currently are warning against putting devices in MRI scanners, with a strong magnetic field could in principle cause the wire of the devices to heat and burn the heart tissue.
Apart from injury to the heart, which could also disrupt the electrical properties of the sensitive devices.
But most research suggests these concerns, which are entirely theoretical, could be to reveal non-based, said Dr. Christopher Kramer, spokesman for the American Association of heart (Haas), who was not involved in the new work.
"With this and several previous studies, there is really no clinically relevant changes that occur in 99.9% of the devices which are digitized," he told Reuters Health.
The AHA does not endorse MRI, short for Imaging by magnetic resonance, in patients with cardiac pacemaker and Medicare does not pay for the scans unless patients are part of a register used to study the safety of the procedure.
In the new study, Dr. Robert Russo and his colleagues at the Scripps Clinic in La Jolla, California, examined the medical records of 109 patients with pacemakers or implantable cardioverter-defibrillators (ICDs). Each was the subject of one or more medically necessary MRI such as analyses to find brain tumours.
The devices were extinguished during the analysis or, if patients did not have a viable heartbeat without them, the value at a constant rate that would be step be disrupted by the magnetic field of the scanner.
There were no deaths, no failure of device and any disorder of the heart rate in one of the patients, according to the study, which was published in the American Journal of Cardiology.
And although there are changes in electrical measurements before and after the analysis, they were not regarded as large enough to have an impact on patients.
In addition, the researchers found the same scale changes when they watched 50 patients with heart that had not been scanned devices, Russo told Reuters Health, indicating that the variation is normal.
He said the findings are not yet definitive and should be confirmed in a larger study, such as the MagnaSafe register, Russo is running.
The Russo and Kramer said more centres began to do MRI on patients with heart devices if there is no other good alternatives.
"If it is clinically necessary the clinician must weigh the risks and benefits on a case-by-case basis," said Russo.
Although U.S. health regulators have already approved a MRI-compatible pacemaker, thousands of patients still live with older models. And between 50% and 70% of people could potentially a MRI, Russo said.
SOURCE: http://bit.ly/U8RH0N American Journal of Cardiology, 27 August 2012 online.
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