The FDA has issued a warning notice about a potential problem with Covidien subsidiary eV3’s Onyx Liquid Embolic System. Rather than recalling the device it seems issuing a warning and modifying instructions for use to raise awareness of the risk of the catheter device becoming entrapped in brain tissues is deemed adequate.
The full warning letter, posted last week, describes the Onyx Liquid Embolic System as a liquid material used to block blood flow in abnormally formed blood vessels in the brain, also know as brain arteriovenous malformations or brain AVMs, before their surgical removal.
Onyx is intended to reduce bleeding and surgical complications when the brain AVM is removed, typically a few days after treatment with Onyx. During the embolisation procedure, the physician uses fluoroscopy to guide the catheter to the site where the Onyx material will be implanted, following which Onyx material is injected through the catheter into the blood vessels of the brain at the location of the AVM. The Onyx material solidifies when it comes in contact with blood in order to block blood flow to the brain AVM.
Since Jan. 1, 2005, the FDA says it has received more than 100 reported cases, including nine patient deaths, of catheter breakage that may be related to catheter entrapment. In some cases the catheter could be removed. 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 (Onyx plug) remained implanted in the patient.
While catheter entrapment is unlikely to affect the physician’s ability to surgically remove the patient’s AVM, neither Onyx nor the catheter is intended be a long-term implant, and patients may need additional medical interventions to have the catheter removed if it becomes entrapped.
The FDA’s warns that complications associated with catheter entrapment can be serious and may include hemorrhage and death. 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.
What to do
Covidien has not issued a recall for the product, FDA seemingly sanguine that heightened warnings about the potential for complication are adequate. Specifically, in April this year, changes were made to the physician and patient labelling that reflect the risks related to catheter entrapment. The labeling also includes recommendations to help minimise the risk of entrapment.