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Medical City Hospital


Troy A. Villarreal — President and Chief Executive Officer

Troy A. Villarreal

Troy A. Villarreal joined Medical City in October of 2013, and has more than 19 years of experience in healthcare. Prior to his arrival at Medical City, he served as CEO of The Medical Center of Plano.

Villarreal has a strong history of community service. He is a member of the Board of Directors of the Dallas / Fort Worth Hospital Council, a member of the Fort Worth Stock Show Syndicate and also serves on the Board of Directors of Cancer Care Services. Additionally, Villarreal has served in the past on the Boards of the Fort Worth Public Library Foundation and North Dallas Chamber of Commerce.

Villarreal is a Fellow in the American College of Healthcare Executives. He earned his BS in Psychology from Texas A&M University in 1989 and his MHA and MBA from the University of Houston-Clear Lake, Texas in 1994. Mr. Villarreal is married and has four children.

Zach Mueller, DNP, RN, NEA-BC — Senior Vice President and Chief Nursing Executive

Zach Mueller

Zach Mueller is Medical City’s Senior Vice President and Chief Nursing Executive. He joined Medical City in 2011, and has more than 15 years of experience in healthcare. As a Registered Nurse, Zach has worked as a clinician in oncology and in the emergency department, and has served in a variety of leadership roles including in director roles over education, pediatrics, and cardiovascular services. Prior to joining Medical City, Zach served as Associate Chief Nursing Officer at The Medical Center of Aurora in Colorado.

Mueller is active in several professional organizations, including the Emergency Nurses Association (ENA), and the American Organization of Nurse Executives (AONE). His career achievements include speaking nationally and internationality on a variety of nursing and healthcare topics, as well as being named a Dallas-Ft. Worth Great 100 Nurse in 2014.

Mueller holds two doctoral degrees, a Doctor of Nursing Practice and Doctor of Nursing from the University of Colorado, as well as a master’s degree in nursing, and two undergraduate degrees. He is board certified by the American Nurses Credentialing Center as a nursing executive, advanced.

Keith V. Zimmerman — Chief Executive Officer, Medical City Children’s Hospital

Keith V. Zimmerman

Keith V. Zimmerman was named CEO Medical City Children’s Hospital in December of 2012 as interim, and permanently in August 2013. Zimmerman has 23 years of healthcare experience, and joined Medical City as Chief Development Officer in January of 2011.

Prior to Medical City, Zimmerman was the System Vice President of Business Development at OhioHealth in Columbus, Ohio. Prior to OhioHealth, Zimmerman has held multiple operational and business development roles in healthcare.

Zimmerman holds a Master’s of Business Administration in Health Care Management from Regis University in Denver with Graduate Honors, along with an undergraduate degree in Business Administration from the University of Louisiana. Mr. Zimmerman is married with two sons.

John Corbeil, Associate Chief Operating Officer

John CorbeilJohn Corbeil joined Medical City in July 2014 and serves as the Associate Chief Operating Officer. In his role he has oversight for multiple operating departments including Pharmaceutical Services, Imaging Services, Free Standing Emergency Department Services, Rehabilitation Services, Food and Nutritional Services, Environmental Services, Security, Parking, HBO/Woundcare and Strategic Internal Communication departments. He also serves as Co-Ethics and Compliance Officer and Chief Staffing Officer for both Medical City and Medical City Children’s Hospital.

Prior to joining Medical City he held the position of Assistant Administrator at Plaza Medical Center of Fort Worth and completed his Fellowship with the HCA North Texas Division. John is a member of the HCA COO Development program and is active in the American College of Healthcare Executives (ACHE).

John earned his undergraduate degree in Business Administration and a Masters of Health Administration from the University of Iowa. While attending the University of Iowa, John was a member of Iowa Student Association of Healthcare Leaders (ISAHL) and played for The University of Iowa Hawkeyes Men’s Ice Hockey Team.