A cardiologist once affiliated with Hamot Medical Center is claiming the hospital and a group of Erie doctors defrauded Medicare by performing unnecessary and costly surgeries involving heart stents. The claims, made in a whistle-blower suit filed in U.S. District Court in Erie, come as the national medical community is scrutinizing angioplasty procedures, which commonly include the insertion of stents -- tiny mesh metal tubes meant to keep an artery open and improve blood fl