FDA approves Eugene doctor’s invention

EUGENE, Ore. — A Eugene doctor’s idea to thread a catheter into the brain of stroke victims to remove blood clots bore fruit last week when the Food and Drug Administration approved the device after nine years of development.

Neuroradiologist J.P. Wensel was searching for a quicker way to remove clots instead of trying to dissolve them with drugs when he first sketched the new medical device nearly a decade ago.

“The quicker you can intervene, remove the clot, restore blood flow, the more brain tissue is going to be viable, and the better the patient is going to do,” he said.

Wensel’s invention, The Merci Retriever, developed by a privately held California company called Concentric Medical, works and looks like a tiny, high-tech corkscrew, but Wensel prefers another term.

“It’s actually not a corkscrew,” he told the Register-Guard newspaper. “I hate that term. It’s a helix of diminishing radius.”

Strokes afflict about 700,000 people annually in the United States. Of those, about 83 percent are ischemic strokes, in which a blood vessel in the brain is blocked by a blood clot.

Strokes killed 163,538 people in 2001 and are the leading cause of serious long-term disability in the United States, as well as the third-leading cause of death.

Concentric Medical’s first test of the device indicates it can play a role in treating people who would otherwise die or be disabled.

“It saved people’s lives,” Wensel said. “That’s a huge personal reward to be a part of something like that.”

The FDA approved The Merci Retriever — Merci is an acronym for Mechanical Embolus Removal in Ischemia — after it was tested on 141 patients at 25 medical centers around the United States.

The device was used on patients who were ineligible for the standard treatment, in which doctors infuse the clot with the drug tPA, or tissue plasminogen activator.

The drug works like Drano to dissolve clots, but if it’s used more than three hours after a stroke occurs, its effectiveness diminishes and it can actually increase the chances of cranial bleeding.

The Merci Retriever, made from a titanium-and-nickel alloy called Nitinol, can be used up to eight hours after a stroke. Of the 141 patients who were treated with the device, 52 percent had their blood flow restored, said Gary Curtis, Concentric Medical’s chief executive officer.

Problems also arose, however.

Device- and procedure-related adverse events occurred in eight of 114 patients, or 7 percent.

Four patients experienced serious device-related adverse events, two had strokes in other parts of the brain, and blood vessels were torn or perforated in two others.

Forty-five patients died after 90 days, two suffered new strokes and two suffered heart attacks.

Another problem involved the device itself. Seven of the 265 devices fractured; of those, six device tips detached in patients, two of which were retrieved.