A blocked coronary artery can lead to a fatal heart attack, and few treatment options exist. Surgeons can thread a tiny, laser-tipped wire through the artery to peck away at the clot, but if that doesn’t work, they may need to perform open-heart surgery, as they do with 360,000 patients a year. Wilmington, MA-based OmniSonics has an alternative: a wire about the width of the thinnest violin string that emits sound waves. Instead of focusing its energy only straight ahead, as lasers do, the wire produces acoustic energy that radiates outward 360 degrees along its entire length, dissolving the clot and other material built up in the artery but leaving the vessel itself unharmed. The company intends to begin testing on cardiac patients before the end of the year and hopes for U.S. Food and Drug Administration approval by late fall.