Less than a year after receiving the FDA go-ahead to sell its Merci L6 Retriever – and about four years after the agency cleared its original Merci Retriever – Concentric Medical (Mountain View, California) has launched its V series Merci Retrievers in the U.S.

These new Retrievers, available in multiple configurations and sizes to match patient anatomy, join Concentric's existing Merci Retrievers already on the market, and provide physicians with additional options for restoring blood flow in patients who have suffered ischemic strokes, the company said.

In 2004 the original Merci Retriever became the first device cleared by FDA to remove blood clots from the brain in patients experiencing an ischemic stroke (Medical Device Daily, Aug. 17, 2004). The device is a catheter that contains a coil-shaped wire that resembles a corkscrew.

According to Concentric, the V series Retrievers have been designed to be the most efficient Merci Retrievers yet and are "the culmination of the company's many years of experience providing neurovascular retrievers for ischemic stroke patients." The distal end of the latest Retriever is tightly coiled, which resists stretching and assists in dislodging clots, Concentric said. The proximal end of the V series Retrievers is more loosely coiled, which facilitates wrapping and holding a dislodged clot. Similar to Concentric's L family of Retrievers, the V series of Merci Retrievers incorporate filaments that provide an additional mechanism for securing blood clots during retrieval from the brain. The V series of Retrievers will be available in diameters of 2.0 mm, 2.5 mm and 3.0 mm.

FDA cleared Concentric's Merci L6 Retriever last September (MDD, Sept. 4, 2007).

An ischemic stroke occurs when a blood vessel in the brain is blocked by a blood clot, which can impair brain function, thus differentiated from a hemorrhagic stroke, which results from a ruptured blood vessel or arterio-venous malformation. Of the 700,000 annual strokes in the U.S., about 87% are ischemic, according to Concentric.

"The Merci Retrieval System is the most widely used clot retrieval system for ischemic stroke, and we continue to incorporate the knowledge gained from our experience, as well as input from many clinicians, into improved devices," said President/CEO Maria Sainz. "These next-generation Retrievers are further evidence of our leadership in bringing exciting and new life-saving options to stroke patients."

The Merci Retriever is made with a flexible, shaped nitinol wire that allows delivery of the Retriever in linear form using standard catheterization techniques. A neurointerventionalist makes a small puncture in the groin to introduce the Merci Retriever into an artery leading to the brain. The Merci Retriever returns to its original shape when deployed in and around the blood clot in the brain.

Concentric's competition in this space includes Ekos (Bothell, Washington), which just last week launched its EkoSonic endovascular system with Rapid Pulse Modulation intended to provide a safer, faster and more complete way to remove dangerous blood clots. The device can deliver microsonic energy and thrombolytic drugs simultaneously, with no evidence of thrombus breakage or hemolysis, according to Ekos (MDD, July 22, 2008).

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