FDA Preliminary1 Public Health Notification: Possible Malfunction of Electronic Medical Devices Caused by Computed Tomography (CT) Scanning

USFDA has issued a very important preliminary notification on possible malfunction of medical devices caused by CT scanning.The number of patients who carry medical devices in India is not known. Since such devices are very expensive the patients carrying them may be very few. According to sun-sentinel.com, in US,tens of millions of patients are outfitted with these technologies, which use electrical currents to help various organs overcome functional deficits.

K.S.Parthasarathy


FDA Preliminary1 Public Health Notification: Possible Malfunction of Electronic Medical Devices Caused by Computed Tomography (CT) Scanning

Date July 14, 2008
Dear Healthcare Professional:
This is to alert you to the possibility that the x-rays used during CT examinations may cause some implanted and external electronic medical devices to malfunction, and to provide recommendations to reduce the potential risk.

Most patients with electronic medical devices undergo CT scans without any adverse consequences. However, FDA has received a small number of reports of adverse events in which CT scans may have interfered with electronic medical devices, including pacemakers, defibrillators, neurostimulators, and implanted or externally worn drug infusion pumps. There have been similar reports in the literature.2-4
It is possible that this interference is being reported more frequently now because of the increased utilization of CT, the higher dose-rate capability of newer CT machines, an increase in the number of patients with implanted and externally worn electronic medical devices, and better reporting systems.
We are continuing to investigate this issue while working with device manufacturers and raising awareness in the healthcare community. To date, no patient deaths have been reported from CT scanning of implanted or externally worn electronic medical devices.
Adverse events
In the reports received by FDA, the following adverse events were likely to have been caused by x-rays from CT scans:
• Unintended “shocks” (i.e., stimuli) from neurostimulators
• Malfunctions of insulin infusion pumps
• Transient changes in pacemaker output pulse rate
Note that malfunctions of this kind, which can result from direct exposure of the medical device to the high x-ray dose rates generated by some CT equipment, are different from those related to MRI scanning, which are caused by strong electric and magnetic fields.
Recommendations
Before beginning a CT scan, the operator should use CT scout views to determine if implanted or externally worn electronic medical devices are present and if so, their location relative to the programmed scan range.
For CT procedures in which the medical device is in or immediately adjacent to the programmed scan range, the operator should:
• Determine the device type;
• If practical, try to move external devices out of the scan range;
• Ask patients with neurostimulators to shut off the device temporarily while the scan is performed;
• Minimize x-ray exposure to the implanted or externally worn electronic medical device by:
o Using the lowest possible x-ray tube current consistent with obtaining the required image quality; and
o Making sure that the x-ray beam does not dwell over the device for more than a few seconds;
Important note: For CT procedures that require scanning over the medical device continuously for more than a few seconds, as with CT perfusion or interventional exams, attending staff should be ready to take emergency measures to treat adverse reactions if they occur.
After CT scanning directly over the implanted or externally worn electronic medical device:
• Have the patient turn the device back on if it had been turned off prior to scanning.
• Have the patient check the device for proper functioning, even if the device was turned off.
• Advise patients to contact their healthcare provider as soon as possible if they suspect their device is not functioning properly after a CT scan.
Background
Experimental studies with anthropomorphic phantoms have demonstrated the potential for high dose rate CT irradiation to affect implanted cardiac rhythm management devices.3,4 Some occurrences in patients, which involved neurostimulator and pacemaker devices, have also been reported to FDA and appear in the literature.3,5
Electronic medical devices that theoretically could be affected by CT x-rays include, but are not limited to:
• cardiac pacemakers,
• implantable cardiac defibrillators,
• neurostimulators,
• drug infusion pumps, including insulin pumps,
• cochlear implants, and
• retinal implants.
While theoretically possible, reports of CT interference with cochlear implants and retinal implants have not been received to date.
Problems with electronic medical devices that might be caused by CT scanner interference include:
• generation of spurious signals, including cardiac defibrillation pulses
• misinterpretation of signals produced by the x-rays as actual biological signals
• missed detection of actual biological signals
• resetting or reprogramming of device settings
The type of effect, if any, is likely to depend on the device type, the manufacturer and the model.
Reporting to FDA
FDA requires hospitals and other user facilities to report deaths and serious injuries associated with the use of medical devices. If you suspect that a reportable adverse event was related to the use of CT equipment, you should follow the reporting procedure established by your facility.
We also encourage you to report adverse events that do not meet the requirements for mandatory reporting. You can report directly to MedWatch, the FDA Safety Information and Adverse Event Reporting program. You may submit reports online at www.fda.gov/MedWatch/report.htm, by phone 1-800-FDA-1088, or by returning the postage-paid FDA form 3500 which may be downloaded from www.fda.gov/MedWatch/getforms.htm by mail to MedWatch, 5600 Fishers Lane, Rockville, MD 20852-9787 or fax 1-800-FDA-0178.
Getting More Information
If you have questions about this Notification, please contact Issues Management Staff, Office of Surveillance and Biometrics (HFZ-510), 1350 Piccard Drive, Rockville, Maryland, 20850, by Fax at 240-276-3356, or by e-mail at phann@cdrh.fda.gov. You may also leave a voicemail message at 240-276-3357 and we will return your call as soon as possible.

FDA medical device Public Health Notifications are available on the Internet at http://www.fda.gov/cdrh/safety.html. You can also be notified through email on the day the safety notification is released by subscribing to our list server. To subscribe, visit: http://service.govdelivery.com/service/subscribe.html?code=USFDA_39.
Sincerely yours,

Daniel G. Schultz, MD
Director
Center for Devices and Radiological Health
Food and Drug Administration

1 CDRH Preliminary Public Health Notifications are intended to quickly share device-related safety information with healthcare providers when the available information and our understanding of an issue are still evolving. We will revise this Notification as new information merits and so encourage you to check this site for updates.
2 “Does High-Power Computed Tomography Scanning Equipment Affect the Operation of Pacemakers?,” Yamaji, S., et al., Circulation Journal 70:190-197 (2006).
3 “Effects of CT Irradiation on Implantable Cardiac Rhythm Management Devices,” McCollough, C., et al., Radiology 243 (3):766-774 (2007).
4 “Hazard Report—CT Scans Can Affect the Operation of Implanted Electronic Devices,” ECRI Institute Problem Reporting System, Health Devices 36 (4):136-138 (2007).
5 MedSun is the FDA's Medical Product Safety Network of 350 hospitals spread throughout the United States. Information from 132 of these facilities indicated that they have not experienced any CT medical device interference, while 3 have had from 1 to 3 events that may have been CT scan induced. Fifteen MedSun facilities indicated they take some precautionary steps when CT scanning patients who have electronic medical devices.
Updated July 14, 2008

New electrostatic-based DNA microarray technique could revolutionize medical diagnostics

U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has invented a technique in which DNA or RNA assays — the key to genetic profiling and disease detection — can be read and evaluated without the need of elaborate chemical labeling or sophisticated instrumentation. Based on electrostatic repulsion — in which objects with the same electrical charge repel one another — the technique is relatively simple and inexpensive to implement, and can be carried out in a matter of minutes.

The news release is prepared very carefully highlighting areas which are yet to be practically realized into the realm of reality!

K.S.Parthasarathy



Contact: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
New electrostatic-based DNA microarray technique could revolutionize medical diagnostics
DNA microarrays can be easily interrogated with only the naked eye using a new electrostatic imaging technique developed in the laboratory of Jay Groves, a chemist with Berkeley Lab,...
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BERKELEY, CA — The dream of personalized medicine — in which diagnostics, risk predictions and treatment decisions are based on a patient's genetic profile — may be on the verge of being expanded beyond the wealthiest of nations with state-of-the-art clinics. A team of researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has invented a technique in which DNA or RNA assays — the key to genetic profiling and disease detection — can be read and evaluated without the need of elaborate chemical labeling or sophisticated instrumentation. Based on electrostatic repulsion — in which objects with the same electrical charge repel one another — the technique is relatively simple and inexpensive to implement, and can be carried out in a matter of minutes.

"One of the most amazing things about our electrostatic detection method is that it requires nothing more than the naked eye to read out results that currently require chemical labeling and confocal laser scanners," said Jay Groves, a chemist with joint appointments at Berkeley Lab's Physical Biosciences Division and the Chemistry Department of the University of California (UC) at Berkeley, who led this research. "We believe this technique could revolutionize the use of DNA microarrays for both research and diagnostics."
A new method for reading DNA (or RNA) microarrays is based on measuring the electrostatic repulsion between silica microspheres and hybridized DNA. Surface areas containing double-stranded DNA (red) or single-stranded...
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Groves, who is also a Howard Hughes Medical Institute (HHMI) investigator, and members of his research group Nathan Clack and Khalid Salaita, have published a paper on their technique in the journal Nature Biotechnology, which is now available online. The paper is entitled "Electrostatic readout of DNA microarrays with charged microspheres."

In their paper, Groves, Clack, and Salaita describe how dispersing a fluid containing thousands of electrically-charged microscopic beads or spheres made of silica (glass) across the surface of a DNA microarray and then observing the Brownian motion of the spheres provides measurements of the electrical charges of the DNA molecules. These measurements can in turn be used to interrogate millions of DNA sequences at a time. What's more, these measurements can be observed and recorded with a simple hand-held imaging device — even a cell phone camera will do.

"The assumption has been that no detection technique could be more sensitive than fluorescent labeling, but this is completely untrue, as our results have plainly demonstrated," said Groves. "We've shown that changes in surface charge density as a result of specific DNA hybridization can be detected and quantified with 50-picometer sensitivity, single base-pair mismatch selectivity, and in the presence of complex backgrounds. Furthermore, our electrostatic detection technique should render DNA and RNA microarrays sufficiently cost effective for broad world-health applications, as well as research."

Your susceptibility to a given disease and how your body will respond to drugs or other interventions is unique to your genetic makeup. Under a personalized medicine plan, treatment effectiveness is maximized and risks are minimized by tailoring disease treatments specifically to you. This requires the precise diagnostic tests and targeted therapies that can stem from assays using a DNA microarray — a thumbnail-sized substrate containing thousands of microscopic spots of oligonucleotides (stretches of DNA about 20 base pairs in length) laid out in a grid.

Often referred to as "gene chips," DNA microarray assays and their RNA counterparts have become one of the most powerful tools for gene-expression profiling, the identification of mutations, and the detection of multiple pathogens in patients afflicted either by multiple diseases or drug-resistant strains of diseases. Aside from their potential future role in personalized medicine, the widespread use of DNA microarray assay devices could have an immediate and profound impact on the treatment of diseases today. For example, according to a report two years ago from the Global Health Diagnostics Forum, 400,000 lives could be saved each year from death by tuberculosis through the use of DNA microarray assays rather than the standard TB diagnostic test, which is known to miss nearly half of all cases.

Until now, however, the use of DNA microarray assays has been limited because current techniques typically depend upon fluorescence detection, a demanding methodology that requires time-consuming chemical labeling, high-power excitation sources, and sophisticated instrumentation for scanning. Such demands are generally well beyond the capabilities of individual laboratories or clinics, especially in developing countries. While label-free DNA detection strategies do exist, they require either complex device fabrication or sophisticated instrumentation for readouts, and in addition none are compatible with conventional DNA microarrays, where up to one million sequences are available for interrogation in a single experiment.

"We have demonstrated parallel sampling of a microarray surface with micron-scale resolutions over centimeter-scale lengths," said Groves. "This is four orders of magnitude larger than what has been achieved to date with conventional scanning-electrostatic-force microscopy."

In a typical experiment, a microarray is prepared and mounted in a well chamber and the DNA is hybridized (a standard technique in which complementary single strands of DNA bind to form double-stranded DNA "hybrids"). A suspension of negatively-charged silica microspheres is then dispersed through gravitational sedimentation over the microarray surface, a process which takes about 20 minutes. Because the substrate or background surface of the microassay is positively charged, the silica microspheres will spread across the entire surface and adhere to it. However, on surface areas containing double-stranded DNA, which is highly negatively charged, and on areas containing single-stranded DNA, also negatively charged but to a lesser degree than double-stranded DNA, the microspheres will levitate above the substrate surface, stacking up in "equilibrium heights" that are dictated by a balance between gravitational and electrostatic forces.

These electrostatic interactions on the microarray surface result in charge-density contrasts that are readily observed. Surface areas containing DNA segments take on a frosted or translucent appearance, and can be correlated to specific hybridizations that reveal the presence of genes, mutations and pathogens.

"Our technique is essentially a millionfold parallel version of the classic experiment used by Robert Millikan almost 100 years ago, when he determined the charge of a single electron by observing the positions of oil droplets levitated above a charged plate," said Groves.

There are a number of short-term "next steps" for this research, Groves said, including testing its application in high-density arrays and pushing its ultimate resolution limits.

"Since the resolution of electrostatic-based imaging is determined by the number of particle-observations rather than by the diffraction limit of light, our readouts could serve as a form of ultramicroscopy," he said. "The real grand challenge for this technology, however, will be for us to find suitable industrial partners with whom we can work to see that useful new products actually make it to market."

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The electrostatic detection technology is now available for licensing through Berkeley Lab's Technology Transfer Department; visit their website at http://www.lbl.gov/Tech-Transfer/index.html.

This research was funded by the U.S. Department of Energy's Office of Science through its Office of Basic Energy Sciences.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at www.lbl.gov.