Dr. Heeren received his M.D. degree in 1974, graduating from Wayne State University in Michigan. He completed his internship and residency in Internal Medicine at William Beaumont Hospital. He also completed a Fellowship in Cardiology at William Beaumont Hospital and is Board Certified in Cardiovascular Diseases.  He has been practicing in Nevada since 1980. He has held the positions of Chief of Cardiology and Chief of Internal Medicine at Sunrise Hospital, and Vice Chief of Staff at Valley Hospital. In 2003 Dr. Heeren served as Chief of Staff for Valley Hospital.  He also served as Co-director at Valley's Department of Cardiology. From 1992 to 1995, he was Chairman of the Special Care Committee (Critical Care) at University Medical Center.

Dr. Heeren's specialties include cardiac catheterization, angiography, Percutaneous Transluminal Coronary Angioplasty (PTCA), coronary stents, temporary and permanent pacemaker insertion and Transesophageal Echocardiography (TEE). He is a member of the American Heart Association and a Fellow of the American College of Cardiology and served on the Board of Directors for the American Heart Association of Southern Nevada.