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Medtronic PLC has paid $150 million plus future performance goals to acquire a California company that makes a self-expanding mesh device to treat weakened blood vessels in the brain.

Medina Medical, based in the venture capital hot spot Menlo Park, Calif., so far only has European approval to sell its Medina Embolization Device to treat brain aneurysms. Medtronic has completed the acquisition, but it didn't announce when the device would be submitted for U.S. approval.

A cerebral aneurysm happens when the wall of an artery in the brain gets weakened, allowing blood to expand into a balloon-like pocket. In severe cases, the aneurysm can burst and lead to hemorrhagic stroke, or put pressure on nerves in the brain. However, many cases can be managed with careful observation alone.

The most common medical-device treatment today is called "coiling," in which a pack of wires is fed through blood vessels via a small delivery catheter and used to fill up the aneurysm. That treatment can become complicated if the aneurysm has too wide of an opening into the vessel.

Medina's new device consists of a self-expanding mesh implant that fills up the aneurysm and provides a "scaffold" across the opening. Medina's website says the company is still in "stealth mode," and the device is not pictured.

"The Medina embolization device features advanced technology to treat cerebral aneurysms that we think can one day disrupt the coil market," Medtronic neurovascular division President Brett Wall said in a news release.

Medtronic previously invested an undisclosed amount for an ownership stake in Medina Medical, and has promised additional payments upon passage of key milestones. The deal is expected to be neutral to 2016 earnings.

Nearly 6 million Americans are believed to have an aneurysm, but most are undiagnosed and unruptured. Roughly 35,000 patients with aneurysms are treated with minimally invasive procedures, and another 21,000 have surgery for it.

Joe Carlson • 612-673-4779

Twitter: @_JoeCarlson