Following a big announcement last January, Boston Scientific Corp. said Thursday it has completed its $100 million acquisition of Plymouth-based Atritech Inc. Additional payments of up to $275 million are contingent on achievement of specified regulatory and revenue-based goals through 2015.

Atritech, run by Twin Cities-based entrepreneur Jim Bullock, has developed the Watchman Left Atrial Appendage Closure device, which is designed for patients with the common heart condition atrial fibrillation who are at risk of suffering from a stroke. The Watchman product closes the left atrial appendage in the heart preventing blood clots, which are fairly common in a-fib patients. Blood clots, of course, can cause a stroke.

Although the device is available in Europe, it hasn't been approved by regulators in the United States. Food and Drug Administration approval has proven a bit elusive for Atritech, which completed an 800-patient clinical trial, but is now enrolling patients in another study to confirm earlier clinical results.

Janet Moore covers medical technology for the Star Tribune.