Tainted Heparin: Where Will the Recall of Medical Devices End?

Minneapolis, MNAfter Medtronic initiated a voluntary recall of various disposable medical devices coated with tainted heparin, the jury is still out as to whether exposure to a smaller amount of the contaminated heparin could prove to be a health hazard.

Over the past several months the news media has been rife with reports about injectable heparin arriving from China found to be contaminated with oversulfated chondroitin sulfate (OSCS)—a chemical that mimics heparin in standard testing and appears to have been added as an inexpensive way to boost volume, but has proven deadly. So far, tainted injectable heparin has been linked to over 80 deaths.

The heparin contaminant was only discovered, and identified after more stringent testing was brought to bear. The result of this discovery led the US Food and Drug Administration (FDA) to recommend that medical device manufacturers test their heparin supplies given the potentiality that some heparin-coated devices might be found to contain the tainted heparin causing so much concern.

That recommendation was issued April 8th of this year, and practically one month to the day later, Medtronic had stepped up to announce that some of its disposable products used during cardiopulmonary bypass (CPB) surgeries were manufactured using heparin known to be contaminated with OSCS.

The affected devices, according to the original release from Medtronic, include items such as blood oxygenators, reservoirs, pumps, cannulae, and tubing packs. Use of these devices would ordinarily be expected to introduce heparin into the bloodstream, but at levels much lower than that inherent with injectable heparin.

In a separate action, Medtronic advised the medical community that selected lots of Trillium-coated products having also been manufactured with contaminated heparin were also in circulation. However, the manufacturer noted that heparin levels used in the Trillium products were significantly lower still, than that used in the Carmeda BioActive surface products and thus, it was felt there was little, if any risk to an individual's health by continuing to use the products. While Medtronic, in the same communiqué, acknowledged that its ultimate goal was to remove all of its product tainted with the contaminated heparin, it put forth the view that "customers can continue to use the affected Trillium products until a replacement is available."

However, no such assurance was issued with regard to the Carmeda BioActive surface products, which is telling. While underscoring the fact that levels of heparin are much lower in the Carmeda products, than that to which patients would be exposed by direct injection of heparin, Medtronic had decided to voluntary recall the products based on the reality that it just didn't know what the affect could, or would be.

"It is unclear…if exposure to Carmeda-coated medical devices, made with comparatively small amounts of heparin, could cause adverse events similar to those observed with injectable heparin formulations," stated a release from Medtronic.

It should be noted that cardio stents were not included in the recall. A stent is a steel mesh device designed to maintain the opening of previously collapsed, or clogged artery following angioplasty balloon catheter procedures intended to open an affected artery in an effort to increase blood flow. However, the addition of a stent usually invites the formation of scar tissue, which can be a good thing if controlled. However, too much scar tissue can effectively re-close an artery.

To combat the problem, drug-coated stents have been introduced in an effort to restrict the formation of scar tissue. Under normal circumstances a patient in receipt of a drug-coated stent will also have to adhere to a concurrent drug therapy in order to control the effect the drug-coated stent has on the artery, and to regulate that impact. Basically, too little scar tissue is just as much a risk as too much: too little, and there is a real danger of a life-threatening blood clot developing.

Such stents are often coated with heparin.

The Medtronic recall did not include drug-coated stents, and it is not immediately clear if Medtronic even manufactures them. However heparin-coated stents, which have been around for at least a decade, are out there. And while the amount of heparin inherent with a drug-coated stent would be less than injectable heparin, the fact remains that given the implantation of the drug-coated, wire mesh stent in the human body, the lower level of heparin might be cancelled out by a constant migration of the heparin into the bloodstream.

What kind of effect that might have on someone is anybody's guess. So far there have been no heparin-coated stents recalled.

Yet…