Medtronic plc has announced that it will buy privately-held device company Twelve, Inc., based in Redwood City, California. Many of you might not have heard of the latter company, as it has chosen not to be in limelight.

Twelve is focusing on the development of a device that aims to repair faulty mitral valves in the heart that can cause congestive heart failure. As per the deal, Medtronic will pay $408 million upfront and another $50 million once the device gets regulatory approval in Europe.

Twelve's investors list includes the venture-capital firms Domain Associates, Versant Ventures and Morgenthaler Ventures. It is second firm that Medtronic has bought by The Foundry, a business incubator in Menlo Park, California.

In 2010, it acquired Ardian, which also a business of The Foundry startup, for $800 million upfront plus milestone payments. Both, Ardian and Twelve were headed by Chief Executive Andrew Cleeland, who is the vice chairman of The Foundry.

Medtronic has made other acquisitions as well, like in June it has bought Aptus Endosystems Inc. of Sunnyvale, California, for around $110 million. It has also acquired Cleveland-based CardioInsight Technologies for $93 million.

In July, Medtronic has said yes to purchase RF Surgical Systems Inc. of Carlsbad, California, for around $235 million. Twelve will soon start the clinical trial of the device on which it is working. For now, the only FDA-approved transcatheter device for treating the mitral valve is of Abbott's MitraClip.