Houston Methodist. Leading Medicine.
Houston Methodist. Leading Medicine

Our Physicians

Methodist Diagnostic Cardiology of Houston

Contact Us

For scheduling please call:
(713) 776-9500.

Medical Office Building One
16651 Southwest Freeway, Suite 400
Sugar Land, Texas 77479
View Map

7777 Southwest Fwy, Suite 420
Houston, TX 77074
View Map

Fax: (713) 776-3087

Monday - Friday
 8:00 a.m. – 5:00 p.m.

Our Physicians

Ronald P. Mahoney, M.D.

College: Ferris State University, College of Pharmacy, 1959
Medical School: Cardinal Stritch School of Medicine, Loyola University, 1963
Internship: Internal Medicine, Cook County Hospital, 1964
Residency: Internal Medicine, University of Iowa Hospital 1968
Fellowship: Clinical Cardiology, University of Iowa Hospital 1970
Board Certified: Internal Medicine, Cardiology and Cardiovascular Diseases


Dr. Ronald Mahoney is an alumnus of Ferris State University, College of Pharmacy. He graduated with his medical degree in 1963 from Cardinal Strich School of Medicine, Loyola University and was the first to apply for an internship at Chicago’s Cook County Hospital.

Dr. Mahoney was the Co-director of Cardio-pulmonary and Coronary Care at Memorial Hermann Hospital-Texas Medical Center for 6 years. He also served as the Director of the Stress Exercise Lab, Echo Lab and Cardiac Cath Lab for 3 years.

Dr. Mahoney served as the first Director of Cardiology Services at Houston Methodist Sugar Land Hospital for 5 years after founding the heart program at Houston’s Memorial Hermann Southwest Hospital and serving as the Director of Cardiology Services, Invasive and Non-Invasive Cardiology Laboratories for 21 years.

Throughout his career, he has spent many years establishing outreach clinics in rural communities, such as La Grange, Halletsville, Cuero, Port Lavaca and Eagle Lake for patients who aren’t able to travel to Houston/Sugar Land for specialized heart care. He has been affiliated with Rice Medical Center in Eagle Lake, Texas for over 25 years.

Dr. Mahoney served in the military as a captain and artillery surgeon in the 1st Infantry Division, 1st Battalion, 7th Artillery in Fort Riley, Kansas and 1st Infantry Division, 2nd Brigade Artillery in South Vietnam. He was awarded the Bronze Star and Vietnamese Medal of Honor in 1966.

Curriculum Vitae

John Passmore, M.D.

Medical School: Vanderbilt University Medical School, 1973
Residency: Medicine, Indiana University, 1976
Fellowship: Endocrinology & Hypertension, Indiana University, 1977; Critical Care Medicine, University of Pittsburgh, 1982; Cardiovascular Medicine, University of Texas Medical School at Houston, 1986
Board Certified: Internal Medicine, Emergency Medicine, Critical Care Medicine and Cardiovascular Diseases


Dr. John Passmore graduated from Davidson College as a Lunsford Richardson scholar and medical school at Vanderbilt University where he was President of the Senior Class. He completed Internal Medicine residency and Fellowship in Hypertension/Endo at Indiana University Medical Center; Fellowship Critical Care Medicine at University of Pittsburgh; and Fellowship Cardiovascular Medicine at University of Texas/Houston.

Dr. Passmore has authored numerous medical textbook chapters and articles in major journals including American Journal of Medicine, Metabolism, and Lancet. He has received board certification in Internal Medicine/Emergency Medicine/Critical Care Medicine/Cardiovascular Medicine, and is a Fellow of the American College of Cardiology and American College of Chest Physicians.

Dr. Passmore is an international medical lecturer on diverse topics and holds membership in Alpha Omega Alpha medical honor society. He has garnered numerous teaching awards including the Joseph Whitehead National Educator of Distinction, John P. McGovern award as Best Medical Professor UT/Houston, Dean's Award UT/Houston, and is 12 time winner of MHSW Residents' Best Faculty Award. Other honors include Chief of Cardiology and PTCA Committee at MHSW along with multiple "Best in Cardiology" listings in Top Doctors Guide, Super Docs, etc.

He is an accomplished pianist with album and an optioned, award-winning screenwriter. Other hobbies include close-up magic, racquet sports, publishing art, and horology (watches). During his residency he served as Ringside Physician for the Indiana State Boxing Commission.

Dr. Passmore believes in a holistic approach to medicine emphasizing physician/patient interaction that allows him to treat and educate his patients in all aspects of their care.

His wife Donna is an attorney and Co-Director of an educational non-profit. They have four grown kids and two grandchildren.

Curriculum Vitae

Earl Mangin Jr., M.D.

Medical School: Louisiana State University Medical School, 1985
Internship/Residency: Internal Medicine, University of Texas Health Science Center, 1988
Fellowship: Interventional Cardiology, Baylor College of Medicine, 1992
Board Certified: Internal Medicine and Cardiovascular Disease


Dr. Earl Mangin is currently the Medical Director of Cardiac Catherization Laboratories at Houston Methodist Sugar Land Hospital and the Sweetwater Angiography Center. He has also been the co-director of the non-invasive lab at Methodist Diagnostic Cardiology of Houston, 1999 to present. His experience is in interventional cardiac peripheral angioplasty and stenting, pacemaker insertion and interrogation, non-invasive evaluation of the cardiac patient, CT angiography and transfemoral aortic valve replacement (TAVR). He has extensive experience in Interventional Cardiology and performed the first coronary intervention in Fort Bend County in 2006 at Houston Methodist Sugar Land Hospital.

Dr. Mangin is part of a team of two cardiovascular surgeons and another cardiologist performing TAVR, a new technology for patients with severe aortic stenosis who cannot undergo traditional aortic valve surgery. There are only four such teams performing this landmark new procedure in the greater Houston area.

Dr. Mangin has participated in animal research placing defibrillators in the inferior vena cava and subclavian veins of laboratory animals in North Carolina for Inner Pulse Technologies. He has published numerous manuscripts and abstracts and presented at national meetings in the field of Endothelium Dependent Relaxation and how it is affected by oxidized LDL. He has lectured, presented abstracts and acted as a moderator on panels for interventional cardiology at national meetings.

Dr. Mangin is a member of the Circulation Council of the American Heart Association, a Fellow of the American College of Cardiology and the Society for Coronary Angiography and Interventions. He has served as a council member for the Houston chapter of the American College of Cardiology and participated in several legislative sessions of Congress to lobby for reform in the health care system.

Curriculum Vitae

B. Keith Ellis, M.D.

College: University of Alabama at Birmingham, 1992
Medical School: Washington University School of Medicine, 1996
Internship: Internal Medicine, Tulane University School of Medicine, 1997
Residency: Internal Medicine, Tulane University School of Medicine, 1999
Fellowship: Cardiovascular Diseases, The Cleveland Clinic Foundation, 2003; Interventional Cardiology, University of Texas Houston Health Sciences Center, 2004
Board Certified: Internal Medicine, Nuclear Cardiology, Cardiovascular Diseases and Interventional Cardiology


Dr. Ellis is the Director of Cardiovascular Services and the Director of the Chest Pain Center at Houston Methodist Sugar Land Hospital. He is an expert in interventional cardiology, and specializes in procedures such as carotid stenting and PFO/ASD closures. Dr. Ellis is also a leading expert in radial artery catheterization, which allows catheterization and stent placement through the wrist. He has extensive experience in the treatment of peripheral arterial disease, including claudication and non-healing ulcers. An expert in cardiac CT angiography, he has been the Director of Nuclear Cardiology for Diagnostic Cardiology of Houston since 2009.

A recognized member of the American College of Cardiology Peripheral Vascular Disease Committee, Dr. Ellis has published a number of scientific manuscripts and book chapters on coronary artery disease, and valvular heart disease. Additionally, Dr. Ellis has presented his data at the American College of Cardiology and American Heart Association national meetings. He is an editorial consultant for the American Journal of Cardiology and Catheterization and Cardiovascular Intervention.

Dr. Ellis is actively involved in clinical trials through the Houston Methodist Research Institute and is the principal investigator of on-going clinical trials at Houston Methodist Sugar Land Hospital. Over the years, Dr. Ellis has won Male Physician of Excellence and Most Respectful awards at the Houston Methodist Sugar Land Hospital Doctor’s Day Ceremony.

A cum laude graduate of the University of Alabama at Birmingham, Dr. Ellis attended Washington University School of Medicine. During his residency at Tulane University School of Medicine, Dr. Ellis won numerous teaching awards, including Charity Hospital Intern of the Year, and was selected to be Chief Resident. He trained in Cardiology at the prestigious Cleveland Clinic Foundation, where he won multiple awards for clinical excellence and research. He finalized his training at the University of Texas Health Sciences Center in interventional cardiology.

Dr. Ellis is a Fellow of the American College of Chest Physicians, the American College of Cardiology, and the Society for Coronary Angiography and Intervention. He is board certified in Internal Medicine, Cardiovascular Diseases, Interventional Cardiology, and Nuclear Cardiology.

As a young man, he earned the rank of Eagle Scout, the highest honor in the Boy Scouts of America.

Curriculum Vitae