In January 2011 Boston acquired Atritech, Inc., for $100 million plus additional potential payments of up to $275 million. Atritech developed a novel device called the Watchman® designed to close the left atrial appendage in patients with atrial fibrillation who are at risk for ischemic stroke. In the same month, Boston Scientific acquired Intelect Medical, Inc. for $78 million and the remaining 86 percent of Sadra Medical, Inc. not already owned for $193 million plus contingent payments. At the same time, the business divested its neurovascular business to Stryker Corporation for $1.5 billion.