After Dr. Mark Midei was accused of implanting unnecessary heart stents in hundreds of patients at St. Joseph Medical Center in Towson, a Maryland Health Care Commission committee began developing safeguards to prevent a repeat situation. But now, one of the committee's members — Dr. John Chung-Yee Wang, a former colleague of Midei's who heads the cardiac catheterization lab at Union Memorial Hospital in Baltimore — is himself accused of improper stenting in three separate legal claims.