Cambridge Heart Inc. cut nearly a third of its employees loose during the first quarter of 2009, as revenues continued to slide in the face of a growing capital equipment sales drought.

The Tewksbury-based cardiac diagnostics maker laid off about 12 employees during the three-month period ended March 31, roughly 30 percent of its 39-person staff, according to a filing with the federal Securities and Exchange Commission. The cuts included more than half of the company’s sales force, as Cambridge Heart looks to streamline its sales operation in part by using outside distributors.

The company currently employs 27 full-time workers.

For the quarter, Cambridge Heart reported $836,000 in sales, a 29 percent decrease from the $1.1 million it reported last year. Despite the slide, the company managed to narrow its losses to $2.2 million, compared to $2.4 million for the same period last year, through a series of cost-cutting initiatives.