FDA Warns About Onyx Liquid Embolic System Catheter Breakage, Deaths

The Onyx Liquid Embolic System (“Onyx”) could increase the risk of catheter breakage and fatalities, according to a new FDA warning.

A safety alert issued by the FDA warns that use of Onyx has been linked to reports of catheter entrapment, which could lead to breakage, hemorrhage and possibly death. Catheter breakage could also result in migration of the Onyx plug or catheter fragment to other parts of the body.

If catheters do break, patients may be required to undergo one or more imaging procedures to locate a piece of the catheter and Onyx plug, increasing their exposure to radiation. Antithrombotic drugs to prevent blood clots around the catheter may also be necessary.

Since 2005, the FDA has received more than 100 reported cases involving problems with the Onyx Liquid Embolic System, including nine patient deaths, where the catheter broke and it may be related to catheter entrapment.

In some cases, the catheter could be removed. However, in at least 54 of these cases, it was not possible to remove the catheter. As a result, part of the catheter and the implanted Onyx material (Onyx plug) remained implanted in the patient. Onyx has not been tested or approved as a long-term implant.

For neuro interventionalists treating patients with brain arteriovenous malformations (brain AVMs), catheter entrapment is unlikely to affect the ability to surgically remove the patient’s AVM.  However, since neither Onyx nor the catheter is intended to be long-term implants, patients may need additional medical interventions to have the catheter removed if it becomes entrapped.

In April 2012, the FDA approved changes to the physician and patient labeling that reflect the risks related to catheter entrapment with Onyx. The labeling also includes recommendations to help minimize the risk of entrapment. According to the FDA, physicians should expect to see this labeling in new orders for Onyx.

The Onyx Liquid Embolic System is a liquid material used to block blood flow in abnormally formed blood vessels in the brain before their surgical removal. A catheter is used to deliver the Onyx liquid to the blood vessel(s) in the brain.

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 Onyx embolization procedure, the physician uses fluoroscopy to guide the catheter to the site where the Onyx material will be implanted. 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.

Fluoroscopy is a type of medical imaging that shows a continuous x-ray image on a monitor, much like an x-ray movie. It is used to diagnose or treat patients by displaying the movement of a body part or of an instrument or dye (contrast agent) through the body. During this procedure, an x-ray beam is passed through the body. The image is transmitted to a monitor so that the body part and its motion can be seen in detail.

The FDA recommends health care providers and neuro interventionalists select patients carefully, after reviewing the most recent device labeling and instructions. Onyx is only approved for use in patients who will undergo surgical removal of the treated brain AVM.

For patients, the potential for catheter entrapment occurs only during implantation. Patients treated with Onyx who did not experience this complication at the time of implantation are not at risk.

Analysis of adverse event reports submitted about Onyx and catheters used to deliver the Onyx material has been conducted and monitoring will continue, says the FDA.