Medical device companies like Medtronic have been under fire lately for their deals with doctors who can influence purchases of medical products, and a Boston doctor says he was fired when he complained about these types of relationships. A lawsuit filed in state court in Massachusetts by David Gossman, an interventional cardiologist formerly on staff at the Lahey Clinic hospitals in the Boston area, who says he complained about Medtronic's offering the hospital a new experimental heart-valve device "predicated on the purchase and increased utilization of other products made by Medtronic." Gossman says he was fired after he complained about the Lahey-Medtronic link in a conversation this summer with Thomas Piemonte, the director of cardiac catheterization at Lahey.