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Researcher Spotlights

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June 25, 2022
Researcher Spotlights – June 2022

Each month, Phoenix Children’s Research spotlights leading physicians and other clinical leaders for their work in the areas of Research, Education and/or Advocacy. For the month of June, we are spotlighting Dr. Steven Zangwill for his work in the field of Research and Dr. Mohan V. Belthur for his contributions to Education, Research and Advocacy.


Steven D. Zangwill, MD

Dr. Steven D. Zangwill

Steven D. Zangwill, MD, has served as medical director of the Heart Transplant and Heart Failure Programs at Phoenix Children’s since 2015. In 2017, he took on the additional role of Director, Heart Center Research. Academically, he is a clinical professor of Child Health at the University of Arizona College of Medicine – Phoenix.

Before joining Phoenix Children’s, Dr. Zangwill served as director of the Pediatric Heart Transplant Program at the Children’s Hospital of Wisconsin, which grew to become one of the nation's busiest heart transplantation programs in the United States. There, he helped establish their pediatric cardiology fellowship program and served as fellowship director. In addition, he was the medical director for the Wisconsin Donor Network.

Dr. Zangwill’s patient care philosophy focuses on being respectful and truthful while shaping communication to best help families understand and effectively process what they need to know. Dr. Zangwill makes it a point to address children as individuals and believes it is important to speak to them directly from an early age. Dr. Zangwill shared he could not imagine being as satisfied doing anything other than what he does now — providing subspecialty care for kids with advanced heart failure.
Dr. Zangwill earned his bachelor of arts degree in psychology and philosophy at Emory University in Atlanta, GA, and his medical degree from Albert Einstein College of Medicine in the Bronx, NY. He completed his pediatric residency at Wyler Children’s Hospital/University of Chicago, and fellowships in pediatric cardiology and cardiac transplant at Babies & Children’s Hospital of New York (Columbia Presbyterian).

Recognized as a Best Doctor in Wisconsin and Arizona for multiple years, Dr. Zangwill is board certified in pediatric cardiology (1998) by the American Board of Pediatrics. He is a member of the Pediatric Heart Transplant Society, the International Society of Heart and Lung Transplant, the ACTION Learning Network and a past member of the American College of Cardiology. 

Dr. Zangwill has presented lectures and workshops at the local, regional, national and international levels, sharing his expertise with a broad audience of learners and professionals. In addition to presenting at professional symposia, he especially enjoys giving talks directly to families. He has served as an invited speaker at several large family-run conferences, including the Mended Little Hearts Symposium and the Transplant Families Conference. He considers it a special honor and a privilege to be able to address large groups of highly engaged families in this context.

Outside of work, Dr. Zangwill enjoys staying active with his family, including traveling, hiking, playing golf and supporting the Green Bay Packers.


It was during his time in Wisconsin that Dr. Zangwill discovered his passion for clinical research, especially translational research. Through the years, he has participated in numerous research efforts. Dr. Zangwill’s key contributions to science include pioneering the virtual crossmatch, developing a novel approach to donor-recipient size matching and using cell-free DNA as a noninvasive marker of rejection in heart transplantation. 

  • Virtual Crossmatch: Early in his experience in heart transplantation, Dr. Zangwill cared for a highly sensitized adolescent supported by a left ventricular assist device as a bridge to transplant. Tragically, despite aggressive perioperative desensitization, the patient developed hyperacute rejection. Bridged with a second device, this devastating complication recurred with a second graft. It was this painful experience that motivated him to develop a better understanding of the pathophysiology behind antibody-mediated rejection and ways to avoid this in sensitized children.

    Collaborating with the histocompatibility team at the Blood Center of Wisconsin, they coined the term virtual crossmatch and applied this practice in a sequential cohort of sensitized children listed for heart transplant. They reported this experience in their 2006 paper entitled The virtual crossmatch: a screening tool for sensitized pediatric heart transplant recipients and the subsequent 2007 paper Practical application of the virtual crossmatch. Virtual crossmatching has since largely supplanted prospective crossmatching as the standard of care for sensitized solid organ transplant candidates.
  • Donor Recipient Size Matching: Dr. Zangwill has been dissatisfied with the conventional strategies for determining size matching in pediatric heart transplantation. Despite dramatic variation in recipient body habitus — ranging from those who may be overweight due to a sedentary lifestyle or who become cachectic in advanced heart failure — the standard metric for donor-recipient size matching remains body weight. In 2013, his group in Wisconsin used MRI imaging to validate an echo-based tool for determining total cardiac volume in both donors and recipients applying this in real-time for size matching at the time of organ consideration.
  • They have gone on to expand this experience and available techniques in Phoenix and have shown in preliminary work that volumetric size matching has the capacity to expand the donor pool for a given recipient, thereby improving overall allocation efficiency, decreasing wait times, saving lives and potentially reducing organ wastage. Dr. Zangwill is currently leading an effort under the umbrella of the Action Learning Network to further develop, validate and apply these techniques through additional study and broad collaboration. He has been invited to participate in the upcoming 2022 American Heart Association Annual Scientific Sessions to discuss this topic.
  • Cell-free DNA as a noninvasive marker of rejection in heart transplantation: With more than 25 years of experience caring for pediatric heart transplant patients, Dr. Zangwill has become increasingly concerned with the risk-benefit ratio of using endomyocardial biopsy as a primary surveillance tool for rejection, particularly in asymptomatic heart transplant recipients. While biopsy is still considered the gold standard, it is fraught with risks, discomfort and inconsistency due to variable sampling and wide interobserver variability.

    Dr. Zangwill has been involved with the DTRT cell-free DNA project — Quantitative Detection of Circulating Donor-Specific DNA in Organ Transplant Recipients  (DTRT) — since its inception and was an integral part in preparing the proposal, conducting the study and the subsequent analysis. His research experience with cell-free DNA has encouraged him to explore this option further as a replacement and/or adjunct to conventional surveillance strategies. This would potentially allow recipients to benefit from more frequent testing at lower risk and providing improved surveillance by detecting graft injury earlier — before clinical sequelae. Dr. Zangwill has participated as a coinvestigator and member of the Steering Committee for the NIH (NHLBI) funded DTRT study. He continues to collaborate with industry and colleagues to explore and expand the use of this technology in pediatric heart transplantation.

Dr. Zangwill is involved in several other ongoing research efforts, including the multicenter TEAMMATE study, a prospective randomized controlled trial evaluating multiple maintenance immunosuppression strategies for pediatric heart transplant patients. He is collaborating with the support of a Phoenix Children’s Foundation Leadership Circle Grant to develop a virtual reality platform for treatment planning and education and has recently been awarded a grant from the Valley Research Partnership to study the presence and clinical implications of anti-vimentin antibodies in pediatric heart transplantation in collaboration with the flow cytometry lab at Dignity’s Norton Thoracic Institute. 

Dr. Zangwill also serves on the Advisory Editorial Board of Pediatric Cardiology, and as a reviewer for the publications Pediatric Transplantation, American Journal of Cardiology, Cardiology in the Young and Circulation.

Dr. Zangwill’s Selected Publications

Complete List of Published Work: 
“Dr. Zangwill is one of our leading academic cardiologists here at Phoenix Children’s. Not only is he a talented and excellent clinician in heart failure, cardiomyopathy and pediatric heart transplantation, he is an extremely bright clinical investigator. His research on cell-free DNA as a novel marker for rejection in heart transplant patients has garnered national and international acclaim, and his work has the potential to break new ground in children who have had a heart transplant. I am proud that Dr. Zangwill and his team are highlighted for their important contributions to our field.” —Wayne J. Franklin, MD, FACC, Co-Director and Robinson Family Endowed Chair, Center for Heart Care; Division Chief, Cardiology; Associate Director, Adult Congenital Heart Disease Program 


Dr. Mohan V. Belthur

Mohan V. Belthur, MD, MS (CTS), FRCSC, FRCS (Tr & Orth), FAAOS, is the director of Pediatric Limb Reconstruction and Neuro-orthopedics in the Division of Orthopedics, and co-director of the Bubba Watson/Ping 3D Human Motion Analysis Laboratory at Phoenix Children’s. Dr. Belthur holds an appointment as associate professor of Orthopedics at the University of Arizona College of Medicine – Phoenix (UA COM-P) and Creighton University School of Medicine in Phoenix, Arizona. His areas of expertise include neuro-orthopedics, limb reconstruction, trauma, musculoskeletal infections, congenital anomalies, foot and ankle disorders and human motion analysis.

Dr. Belthur attended medical school at Bangalore Medical College in Karnataka, India and completed his residency at Seth GS Medical College, KEM Hospital in Mumbai, India, West Midlands Orthopedic Training Program in Birmingham, UK, and All Wales Higher Training Program in Cardiff, UK. He completed fellowships in pediatric orthopedics at Alfred Dupont Hospital for Children in Wilmington, Delaware; limb reconstruction at Sinai Hospital of Baltimore in Baltimore, MD; and pediatric orthopedics and scoliosis at Baylor College of Medicine in Houston, TX. He is board-certified in trauma and orthopedic surgery in India, Canada, the UK, and the USA. Before moving to Arizona to join Phoenix Children’s in 2013, Dr. Belthur worked as a pediatric orthopedic surgeon in India and at Sinai Hospital of Baltimore.

Dr. Belthur had his first exposure to orthopedics when he injured his elbow, leg and foot as a child. Later, battling a serious illness during medical school taught him even more about the difficulties patients can face and the value of receiving excellent healthcare.

Dr. Belthur has been recognized as a Castle Connolly Top Doctor since 2012, and as the UA COM-P Scholarly Project Mentor of the Year in 2020. His experiences continue to inspire his compassionate and empathetic approach to patient care. As an orthopedic surgeon, he strives to improve the lives of children, adolescents and young adults with musculoskeletal problems.
"I love working with children and their families, being able to solve challenging problems and make a difference in their lives," Dr. Belthur shared.

Dr. Belthur lives with his wife, a software engineer who runs her own business, and 14-year-old daughter. When he is not working, Dr. Belthur enjoys traveling with his family and visiting national parks and cultural heritage centers worldwide. His hobbies include practicing and teaching yoga, hiking and biking. He holds a second-degree red belt in Tang Soo Do, a karate-based South Korean martial art, and is currently training for his black belt at the Center for Human Living. His interests also include reading about leadership and well-being, history and ancient Indian scriptures.

Dr. Belthur on Research

As co-director of the Bubba Watson/Ping 3D Human Motion Analysis Laboratory, Dr. Belthur and his team analyze human walking in three dimensions and solve challenging gait problems in children and young adults to optimize their walking, function and quality of life. He is involved in many multicenter research collaborations, including Infrastructure for Musculoskeletal Pediatric Acute Care Clinical Trials (IMPACCT), International Limb Differences Study Group, Pediatric Limb Deformity study group and Musculoskeletal Infections in Children Consortium (MUSICC).

Asked about his most impactful research project, Dr. Belthur shared his study on Pathologic fractures in children with acute Staphylococcus aureus osteomyelitis. This study was significant as it concluded, “Staphylococcus aureus osteomyelitis is a serious infection that may predispose children to pathologic fractures. Protected weight-bearing and activity restriction are recommended in children with Staphylococcus aureus osteomyelitis who have the risk factors demonstrated in this study.”

Dr. Belthur is also involved in global health. He works with nonprofit organizations focused on easing the burden of childhood musculoskeletal disorders in low- and middle-income countries.

Dr. Belthur has published 75 peer-reviewed publications and 20 book chapters, and is currently editing a book on Pediatric Musculoskeletal Infections: Principles & Practice, available July 8, 2022. 

Dr. Belthur’s Selected Publications 

•    Perceived Physician Empathy in Pediatric Orthopedics: A Cross-Sectional Study
•    Motion laboratory gait analysis and orthopedic resident education: preliminary results
•    Progressive Ankle Subluxation Following Panfibular Osteomyelitis Requiring Fibular Resection
•    Ethnic and Sex Diversity in Academic Orthopaedic Surgery: A Cross-sectional Study
•    Clinical Scores Predict Acute and Chronic Complications in Pediatric Osteomyelitis: An External Validation

Complete List of Published Work:

Dr. Belthur on Education

Dr. Belthur’s clinical and academic interests include pediatric limb reconstruction, pediatric neuromuscular disorders and 3D gait analysis, pediatric foot and ankle disorders, pediatric trauma and musculoskeletal infections, patient-reported outcomes and diversity and inclusion in orthopedics.

Dr. Belthur is passionate about teaching, mentoring and connecting, whether with patients and families or other health professionals. “Mentoring students has been a wonderful experience, and I enjoy guiding them and influencing their professional development and career trajectory,” shared Dr. Belthur about his experience as a scholarly project mentor. “I like helping them with their resumes, developing their research and writing skills, and furthering their interest in pediatric orthopedics.”

He went on to explain that while he loves research and clinical work, education is his favorite part of his job. He noted, “Being a doctor means to educate. Being able to work with medical students and pass my knowledge on to them so they can learn and become better than I am makes my life more fulfilling and enjoyable.”

Dr. Belthur gives his time generously to medical students and early career faculty as an active mentor affiliated with several mentoring programs. He is a founding member of Building Next Generation of Academic Physicians (BNGAP) – Phoenix, AZ chapter; Phoenix Children’s Hospital Mentorship Program; UA COM-P’s Mentorship Program and White Coats for Black Lives Program; Faculty Advisor to the orthopedic interest group at the UA COM-P; Instructor, Simulation Lab, UA COM-P; Faculty, Department of Orthopedics – Phoenix Children’s Hospital and Pediatric Orthopedic Society of North America (POSNA) Mentorship Program.

Dr. Belthur is interested in leadership, faculty development and wellbeing. He completed several leadership development programs, including UA COM-P Leading and Inspiring Faculty Trajectories (LIFT) Faculty Mentorship Program, 2018-2020; Faculty Leadership Development Program at UA COM-P, 2020; Stanford Physician Wellbeing Director’s Course, 2021; and Stanford Physician Leadership Certificate Program, 2022. He holds a leadership position on UA COM-P Faculty Development Committee, POSNA Education Committee, Limb Lengthening and Reconstruction Society (LLRS) Communications Committee, and American Academy for Cerebral Palsy and Developmental Medicine (AACPDM) Care Pathway Committee.

Dr. Belthur on Advocacy

Dr. Belthur is involved in diversity and inclusion, and global health initiatives at Phoenix Children’s and UA COM-P, sharing the mission for providing hope, healing and the best healthcare, and he appreciates being part of organizations that promote diversity and inclusion. 

Dr. Belthur supports these initiatives through his service locally and internationally as a board member for Raising Special Kids, a nonprofit organization helping parents with special needs access services in Arizona; as a member of the Medical Advisory Board, Serve Together Foundation, India, a nonprofit organization that aims to provide sustainable care for children with clubfeet in India; and as a lifetime member and international advisor for the Pediatric Orthopedic Society of India.

“Dr. Belthur truly defines an accomplished physician leader excelling in both clinical and research areas. Through his work, he has improved the lives of many children in our community and globally with orthopedic issues. I have had the privilege to work with Dr. Belthur for the past 10 years and have witnessed his dedication to patients, students and colleagues. He is deeply passionate about teaching and mentoring, and this is evident in the many successful research projects of medical students he sponsors in his lab. He is also passionate about promoting diversity and inclusion within the medical field and is involved in many local and national outreach projects in this area. He is an inspiration to many, and I am happy he helps make Phoenix Children’s Hospital one of the best in the nation.” —Deborah J. Tom, MD, Neonatologist & Chair of Phoenix Children’s Medical Student Mentorship

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