(UPDATED: See below.)

arbor-surgical-logo-250px.gifIrvine, Calif.-based Arbor Surgical Technologies, a developer of minimally invasive heart-valve replacement devices, raised another $5.5 million in its third funding round, VentureBeat Life Sciences has learned. The cash came courtesy of the Laguna Fund, a new investor, and Delphi Ventures and Alloy Ventures, which have participated in previous funding rounds.

Arbor said it raised $20 million in the round in late January, so the extension brings that round to a total of $25.5 million. The company’s CEO, Steve Bacich, didn’t return a phone call or an email seeking comment.

Arbor, founded in 2002, is currently conducting European clinical tests of its replacement device for the heart’s aortic valve, which controls the flow of oxygen-rich blood from the left ventricle into the aorta. The valves are made of bovine pericardium, the tough tissue sac that surrounds a cow’s heart.

Many existing aortic-valve replacements require open-heart surgery; Arbor says its device can be implanted in a minimally invasive procedure, although it doesn’t describe the procedure in any of its available public information. The company plans U.S. trials of the device later this year. In January, Arbor licensed manufacturing, marketing and distribution rights to the device to Medtronic in exchange for an equity investment and, most likely, other undisclosed payments.

Of course, no Valentine’s Day would be complete without some messy pictures of heart surgery. I’ve put an Arbor photo comparing the implantation of its device to that of traditional aortic-valve replacements after the jump.

UPDATE: Bacich got back to me about ten minutes after this post went up — which was close to three hours after I called and emailed him — and said he doesn’t know anything about this funding. He’s running down the facts, and I’ll update again when I know more. He also said that Laguna is an existing investor — according to Bacich, it’s a “branch” of funds owned by Arbor co-founder Thomas Fogarty. Laguna isn’t listed as an investor on the Arbor Web site, although Fogarty is.