The FDA issued a safety alert after receiving reports of more than 100 adverse events, including 9 patient deaths, that may have been caused by Onyx brain blood vessel plugs made by Covidien (NYSE:COV) subsidiary ev3 Inc.

The Massachusetts-based device maker hasn’t issued a recall on the Onyx product, a liquid embolic system designed to block blood flow to problem blood vessels before surgical removal, but the FDA approved new device labeling indicating the risk of "catheter entrapment," in which the device’s delivery catheter becomes stuck in brain.

The Onyx product is delivered to the brain via catheter, and since Jan. 1, 2005, the FDA has received 100 reports of the catheters becoming stuck in patients’ brains.

"In at least 54 of these cases, it was not possible to remove the catheter, so part of the catheter and the implanted Onyx material remained implanted in the patient," according to the FDA warning.

The device, made by Covidien subsidiary ev3 Inc., is a spongy material that hardens when it comes into contact with blood. The Onyx liquid is injected through the catheter to the brain vessel site, and entrapment occurred when the catheter became stuck in the hardened Onyx material, according to the report.

"The clinical data submitted by the manufacturer prior to marketing included cases where the delivery catheter was difficult to remove, but in all cases the catheter was removed without any adverse patient events," the federal watchdog agency noted. "The original product labeling did not reflect the risks related to catheter entrapment but new labeling will include these risks as well as recommendations to help minimize that risk."

Catheter entrapment isn’t likely to hinder a physician’s ability to surgically remove problem brain vessels, but neither the Onyx device or the catheter delivery system were intended to remain in the brain for long periods of time, the FDA cautioned.

"Complications associated with catheter entrapment can be serious. The most serious complications include hemorrhage and death," according to the report. "Other complications include migration of the Onyx plug or catheter fragment to other parts of the body. Patients with catheter entrapment may need to take antithrombotic drugs to prevent blood clots around the catheter, and may need to undergo one or more imaging procedures to locate a piece of the catheter and Onyx plug, increasing their exposure to radiation."

The agency warned surgeons to avoid aggressive attempts to remove stuck catheters as that could result in catheter breakage or brain hemorrhage. The FDA asked surgeons to note the manufacturers instructions for removing an entrapped catheter, and to report any new incidents for ongoing monitoring.

Covidien representatives did not immediately return requests for comment.

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