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Troy A. Villarreal, FACHE

President and Chief Executive Officer, Medical City Dallas Hospital

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.

Troy 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, Troy has served in the past on the Boards of the Fort Worth Public Library Foundation and North Dallas Chamber of Commerce.

Troy 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. Troy is married and has four children.

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

Keith 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. Keith is married with two sons.

Susan Shreeve

Chief Financial Officer, Medical City Dallas Hospital & Medical City Children's Hospital

Susan Headshot Revised

Susan Shreeve, CPA, received both her Bachelors of Science and Masters of Accountancy degrees from Brigham Young University. She began her career as a CPA with Ernst and Young in Riverside, California with a focus on: Acute Care Hospitals; Post-Acute Care Hospitals; and Physician Groups. She was subsequently recruited by two of her longtime clients: San Bernardino Community Hospital and Loma Linda University Medical Center.

While working for Loma Linda University Medical Center, Susan was asked to become the Sr. Vice President of Finance for a newly developed organization: Loma Linda University Health Care. Loma Linda University Health Care’s charter was to merge 20 physician specialty groups as part of an integrated delivery system.

Susan joined HCA in 1997 as Chief Financial Officer for Bayshore Medical Center in Pasadena, Texas. Susan transferred to Kansas City as Chief Financial Officer for Research Medical Center, Belton Regional Medical Center, and Research Psychiatric Center in 2004.  Currently, Susan is the CFO for Medical City Dallas.

Susan and her husband, Mark, are the parents of two sons, Tanner and Jacob.

Michael Gruber, M.D.

Chief Medical Officer, Medical City Dallas Hospital & Medical City Children's Hospital

Michael Gruber, M.D.

Michael Gruber, M.D., was named Chief Medical Officer at Medical City Dallas Hospital in August 2015. Dr. Gruber is a board certified urologist and a tenured leader at Medical City, and he has served on the medical staff since August 1982. As Chief Medical Officer, Dr. Gruber leads Medical City’s overall clinical strategies and works with physicians to emphasize patient safety, patient care and quality outcomes.

Dr. Gruber was President of the Medical Staff in 2013, then Chairman of the Privileges and Credentials Committee in 2014. He is a member of the American Urologic Association, Texas Medical Association, Dallas County Medical Society and the South Central Section AUA. He has been named one of D Magazine's Best Doctors each year from 2001 through 2015. Additionally, he was chosen as one of Texas Monthly's Super Docs from 2004 through 2015.

Dr. Gruber graduated with honors from the University of Texas at Austin where he was a member of the Phi Beta Kappa Honor Society. He completed medical school and his urology residency at the University of Texas Medical Branch in Galveston, and he completed his surgical internship at the University of California in San Diego.

Zach Mueller, DNP, RN, NEA-BC

Senior Vice President and Chief Nursing Executive, Medical City Dallas Hospital

Zach Mueller

Zach Mueller, DNP, RN, NEA-BC, 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.

Zach 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.

Zach 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.

Angie Buckmeier, MHA, BSN, RN

Chief Nursing Officer, Medical City Children's Hospital
Vice President of Nursing for Women’s & Children’s, 
Medical City Dallas Hospital & Medical City Children's Hospital


Angie Buckmeier joined the senior leadership team at Medical City Children’s Hospital in 2015 to serve as the Chief Nursing Officer and Vice President of Nursing for Women’s & Children’s Services. With more than 26 years of nursing experience and 23 years at Medical City, Angie started her career as a pediatric staff nurse and progressed through a variety of leadership roles in pediatrics including the specialties of general pediatrics, oncology, craniofacial and well-baby newborn care. Angie also served in leadership roles for Women’s services as the manager of Postpartum and Director of Women’s Services. Prior to her current role, Angie served as Director of Nursing for maternal and infant services at Parkland Health and Hospital System.

Angie’s key accomplishments in her leadership roles include maintaining staff turnover under national benchmarks, achieving and maintaining the highest patient satisfaction scores in the organization, impressive quality improvement and outcomes in CLABSI, falls, and exclusive breastfeeding, among others.

Angie received her Master of Healthcare Administration degree from University of Phoenix, her Bachelor of Science degree in nursing from University of Louisiana at Monroe, and was named a 2010 DFW Great 100 Nurse. Angie is married and has two sons.

Jay deVenny, FACHE

Vice President of Business Development, Medical City Dallas Hospital

Jay Devenny Headshot

Jay deVenny, FACHE, is the Vice President of Business Development at Medical City Dallas Hospital. In this role, Jay supports all service line strategic development and coordinates the strategic planning process while integrating hospital operations and affiliation development.  His leadership has strengthened multiple tertiary service lines including neurosurgery, orthopedics, heart and vascular, GI, oncology, bariatrics and transplantation.

Prior to joining Medical City, Jay spent seven years leading various administrative and business development roles within Baylor Health Care System. He served as director of professional services at Baylor Regional Medical Center at Plano from 2008 through 2013, where he grew scoliosis, orthopedic oncology, weight loss surgery and pain management service lines. Additionally, he opened satellite scoliosis clinics in Fort Worth and Fort Lauderdale, Florida. Jay also served as a marketing and public relations consultant and administrative resident at Baylor Regional Medical Center at Plano, championing business development and operational initiatives.

Jay holds a Bachelor’s in Communication Studies from University of Kansas, a MBA in Health Services Management from University of North Texas and is a Fellow of the American College of Healthcare Executives (FACHE).

Jay enjoys spending time with his wife, Betsy, and two children, Hunter (5) and Harper (2). He enjoys playing golf and traveling with his family. 

John Corbeil

Associate Chief Operating Officer, Medical City Dallas Hospital

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, John 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.