Dr. Fleissner's practice is part of BJC Medical Group of Illinois, a well-established, multi-specialty physician group. He specializes in diagnosing and treating heart disease, such as congenital heart defects, coronary artery disease, heart rhythm disorders and heart failure. Additionally, he specializes in invasive cardiology procedures such as angioplasty, atherectomy, cardiac catherizations, coronary and drug coated stents.