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Jeffrey A. Singer, M.D., F.A.C.S.

Board Certified General Surgeon

Dr. Singer is President Emeritus and founder of Valley Surgical Clinics.

He is a senior fellow at the Cato Institute and works in the Department of Health Policy Studies.  Dr. Singer received his M.D. from New York Medical College in New York City, where he was elected into Alpha Omega Alpha (Iona Chapter), the Honor Medical Society. He completed his Surgical Residency at Maricopa County General Hospital, Phoenix, Arizona. He is Board Certified in the specialty of General Surgery. He has over 30 years of experience in his field of general and laparoscopic surgery. Dr. Singer is a Fellow of the American College of Surgeons, the International College of Surgeons, the Southwestern Surgical Congress, & the American Society of Abdominal Surgeons.


Francisco Rodriguez, M.D., F.A.C.S.

Board Certified General Surgeon

Received his M.D. from the Catholic University in Santiago, Dominican Republic. Dr. Rodriguez completed his Internship in General Surgery at Indiana University and Purdue University Hospitals in Indianapolis, Indiana. He completed a General Surgery Residency at the University of Illinois at Chicago, Cook County Hospital, after which he went on to a fellowship in Transplant Surgery at Ohio State University School of Medicine in Columbus, Ohio.

His experience in transplant surgery has given him a special expertise and interest in major pancreatic and liver surgery, in which he has earned a local reputation for excellence. He has become a Phoenix-area leader in the performance of laparoscopic Nissen fundoplication for severe gastro-esophageal reflux disease.

Continually striving to provide superior patient care along with advantages of the latest technology, Dr. Rodriguez and partners began training in 2008 in Robotic assisted surgery.

As one of the founding members of the Clinical Robotic Surgery Association, Dr. Rodriguez and his partners are paving the way in Robotic assisted surgery with new innovations and refinement of techniques. As a group they have successfully performed over 300 Robotic Surgeries to date.

In 2009, Valley Surgical Clinics had the pleasure of hosting to the first ever Robotics Symposium in Phoenix. Dr. Rodriguez was a featured key-note speaker on Robotics in Private Practice at this event.

Dr. Rodriguez is among a small group surgeon in the United States to perform daVinci® Robotic Thyroid and Parathyroid Surgery. He and his partners are quickly building one of Arizona’s largest Robotics programs using this new procedure. His early experience allows him to train other local surgeons, and develop training programs at local hospitals.

Dr. Rodriguez is Board Certified in the specialty of General Surgery. He is a C.A. Professor of Surgery University of Illinois, Chicago. Dr Rodriguez is a Fellow of the American College of Surgeon, the International College of Surgeons, and the southwestern Surgical Congress. Dr Rodriguez founded the non-profit group the Arizona Dominican Medical Friends in 2005.  He has taken Surgeons of various specialties and Surgical Nurses on more than 20 missions to Santiago, Dominican Republic.  This team has performed hundreds of life changing surgeries to the indigent of this country.  Through his commitment to serving his native country he has worked to partner with local healthcare institutions to foster surgical advancements in Laparoscopic and Robotic surgery.  Dr. Rodriguez is fluent in Spanish.


Luis Hashimoto, M.D., F.A.C.S.

Board Certified General Surgeon

Dr. Hashimoto received his MD from San Marcos National University School of Medicine in Lima, Peru. Dr. Hashimoto’s post-graduate training was done at the Cleveland Clinic in Cleveland, Ohio where he received the Resident Achievement Award presented by the Society of Laparoendoscopic Surgeons. He studied abroad at Tohoku University in Sendai City, Japan where he received his PhD (Doctor in Medical Science). At Tohoku University he also received additional training on hepatobiliary and gastric cancer surgery, abdominal ultrasound, and was a member of the Liver Research Group.  Dr Hashimoto is the acting Residency Associate Program Director at HonorHealth in Phoenix.  Dr. Hashimoto is fluent in Spanish and Japanese.


Roozbeh Rassadi, M.D., F.A.C.S.

Board Certified General Surgeon

Dr. Rassadi comes to Valley Surgical from Methodist Dallas Medical Center. He went to McGill University in Montreal, Canada where he obtained his masters in Physiology. He completed his residency in General Surgery at Drexel University College of Medicine in Philadelphia, Pennsylvania. He received the Golden Stethoscope nominee for excellence in teaching as a resident. Dr Rassadi then completed his fellowship in Upper GI/Hepatobilliary Surgery at Methodist Dallas Medical Center. Dr. Rassadi is a Candidate Member of the American College of Surgeons. Dr. Rassadi was a member of the Editorial Board for the McGill Journal of Medicine.  Dr Rassadi is Chief of Staff at HonorHealth Care North Mountain campus and is a part of the Residency faculty team.  Dr. Rassadi is fluent in Farsi.


Scott Hillmann, M.D., F.A.C.S.

Board Certified General & Vascular Surgeon

A board-certified general surgeon, Dr. Hillmann earned a bachelor’s degree in biology at the University of Delaware and a medical doctorate at George Washington University. After completing a surgical internship and general surgery residency at Rhode Island Hospital, he moved to Phoenix for a vascular surgery fellowship at Good Samaritan Hospital.


He has practiced in the Valley since 1982 focusing on all aspects of general and vascular surgery, performing his own angiograms and angioplasties as well as endoluminal aortic aneurysm repairs.


Mytia McNeal, M.D., F.A.C.S.

Board Certified General Surgeon

After earning a Bachelor’s degree at Michigan State University in Lansing, Dr. McNeal graduated from the Wayne State University School of Medicine in Detroit, Mich. She then completed both her internship and residency at the Loyola University Medical Center in Maywood, Ill.


With special interests in wound care and breast surgery, Dr. McNeal has received several honors and is active in a number of professional organizations. She is board certified in general surgery.


Christi Bourne, M.D., F.A.C.S.

Board Certified General Surgeon

Christi Bourne, MD, FACS, received her MD from University of California, Davis, and then completed her general surgery residency at Boston University Hospital. She graduated magna cum laude from UCLA/University of London with a BA in English literature, and is a member of Phi Beta Kappa. In 1990,  she began her practice in breast and general surgery with Valley Surgical Clinics, leaving in 1995 to establish the Valley's first breast only practice. In 2014, she rejoined VSC, and continues to treat breast cancer and related conditions exclusively.

She is a member of the American Society of Breast Surgeons, a board certified Fellow of the American College of Surgeons, and an active member of the Breast Program Leadership Committee at HonorHealth.
In addition to raising her own two children, she has volunteered for Big Sisters, Maricopa County Crisis Nursery, and most recently, as a foster parent providing respite care through AASK (Aid to Adoption for Special Kids). 


Mohan Ramalingam, M.D.

Board Certified General Surgeon

Mohan Ramalingam, M.D. is an American board-certified General Surgeon as well as an accredited fellowship trained Bariatric Surgeon.

He graduated in 2004 from the National University of Singapore, Faculty of Medicine which is affiliated with Duke University (Durham, NC). He became a Member of the Royal College of Surgeons (Edinburgh) in 2008 and obtained his Master’s degree in Surgery from the National University of Singapore in 2009.

He moved to the United States in 2009 and from 2010 to 2015, completed his General Surgery training at the Phoenix Integrated Surgical Residency - University of Arizona program and obtained American Board of Surgery certification. 
From 2015 to 2016, he received additional sub-specialty fellowship training at the University of Miami - Jackson Memorial Hospital (Florida) in Advanced Laparoscopic Foregut and Bariatric (weight-loss) Surgery. He is a member of the American College of Surgeons, the Society of American Gastrointestinal and Endoscopic Surgeons and The Obesity Society.

After completing his training, Dr. Ramalingam joined Valley Surgical Clinics in 2016 and has held various leadership positions in several HonorHealth and Abrazo campuses. Over the next several years, consistent performances in his work culminated in him winning the distinguished Top Doc award in 2023 after he garnered the greatest number of votes from his peers in the field of General Surgery.

He performs complex laparoscopic as well as robotic foregut surgeries including gastrectomies for gastric tumors and cancers, hiatal hernia repairs, small bowel and colon resections. He also performs bariatric and weight loss surgeries including gastric sleeves, bypasses, duodenal switches and revisional bariatric procedures.

He is fluent in English, Tamil and basic conversational Mandarin and spends his free time playing tennis and soccer with his 2 children. He travels widely, loves to read and attends medical conferences to keep himself up to date with the latest technologies and state-of-the-art surgeries. He also enjoys volunteering at various charities both at home and abroad. 


Varun Chakravorty, M.D., F.A.C.S.

Board Certified General Surgeon

Dr. Chakravorty completed his undergraduate studies at the University of Western Ontario.  After completing medical school at St. George University School of Medicine in Grenada, he completed his general surgery residency at Saint Barnabas Medical Center in Livingston, New Jersey. He has been in Phoenix since 2018 and is a highly respected surgeon performing complex robotic surgery as well as laparoscopic and open operations. His expertise with robotic surgery has allowed him to become a registered proctor with Intuitive, which allows him to teach other surgeons to use the daVinci robot and increase their proficiency.

He has held multiple leadership positions during this time. He served as the Chairman of Surgery at Abrazo Scottsdale Campus and is the current Vice Chief of Staff over the Abrazo Central and Abrazo Scottsdale Campus. He is part of the core faculty for the HonorHealth General Surgery residency program where he has taken a special interest in developing a simulation curriculum for the residents.

He is also active in the community where he has led outreach events to educate the public on robotic surgery and its applications.


Erin Kloos, M.D.

Board Eligible General Surgeon

Dr. Kloos graduated from the University of Washington with a Bachelor’s of Science in Biology.  She completed Medical School at the University of Arizona College of Medicine, while also doing 3 medical mission trips to Honduras, Dominican Republic and Haiti and completed General Surgery Residency at the University of Arizona College of Medicine - Phoenix Integrated Surgical Residency & Banner University Medical Center.  Dr. Kloos is Board Certified by the American College of Surgery.


Gabriel Mekel, M.D.

Board Certified General Surgeon

Dr. Mekel is a board-certified general surgeon who graduated from medical school with the Magna Cum Laude distinction at Universidad Central de Venezuela. He then moved to the USA where he started his general surgery residency training at Drexel University College of Medicine / Hahnemann University Hospital in Philadelphia, PA and then completed it at Saint Barnabas Medical Center in Livingston, NJ. During residency, he received the Dennis R. Filippone Chairman Award, the Academic Achievement Award and the Robert S. Dorian Teaching Award. In addition, he served in the Graduate Medical Education Committee as well as the Surgery Residency Program Evaluation Committee. Dr. Mekel then continued his fellowship training in Minimally Invasive, Bariatric and Foregut Surgery at Geisinger Medical Center in Danville, PA. Currently he is a member of the Abrazo Health Credentials Committee. Dr. Mekel has authored numerous papers and performs a wide variety of open, laparoscopic and robotic procedures.  Dr. Mekel is fluent in Spanish.


Kei Nagatomo, D.O.

Board Certified General Surgeon

Dr. Nagatomo graduated from the University of Arizona with a bachelor’s degree in Molecular Cellular Biology. He completed medical school at Kirksville College of Osteopathic Medicine in Missouri and general surgery residency at Lankenau Medical Center-Thomas Jefferson affiliated program in Wynnewood, PA. During his residency, he received the intern of the year award in 2013, the medical student teaching award, and the clinical research award. During his surgical training, Dr. Nagatomo completed a one-year research fellowship on pancreatic cancer. He then completed an advanced gastrointestinal/complex gastrointestinal surgery fellowship at Methodist Richardson Medical Center in Richardson, Texas, focusing on foregut and hepatobiliary surgeries. Before joining Valley Surgical Clinics, he practiced as a general surgeon in Louisiana and served as a medical student clinical preceptor at the University of Louisiana Monroe (VCOM-Monroe). Dr. Nagatomo provides comprehensive care for various acute and chronic surgical conditions. He is passionate about helping his patients and enjoys the challenges related to managing complex gastrointestinal surgical diseases. He focuses on the “total care of a patient” mentally and physically. He believes that the best medical care is achieved when a surgeon considers surgical issues from the patient’s perspective.  Dr. Nagatomo is fluent in Japanese.


Peter Ferrara, M.D., F.A.C.S.

Board Certified General Surgeon

Dr. Ferrara is fellowship trained in surgical oncology. His fellowship was at The Ohio State University.  He attended medical school at New York University and completed his residency as well in New York. He moved to the valley in 1989, and was a commissioned officer in the public health service, working at the Phoenix Indian Hospital. He then served for 10 years as the chief of surgical oncology at Maricopa Medical Center before entering private practice in 2000. He joined Valley Surgical Clinics in 2021 and is currently the Chief of Surgery at Scottsdale Shea Campus. He enjoys seeing all patient with general surgery issues, especially those with newly diagnosed malignant tumors.


Chester Hayes III, M.S., PA-C

Certified Physician Assistant

Mr. Hayes, our Certified Physician’s Assistant, earned his undergraduate degree in Athletic training/corporate fitness and wellness from Grand Canyon University in 1994. He completed post-graduate studies at Arizona School of Health Sciences in Phoenix, Arizona to become a Physician’s Assistant in 2003. Mr. Hayes has been working with Valley Surgical Clinics, LTD., since 2006. Mr. Hayes is an active member of the American Academy of Physician Assistants, Arizona State Academy of Physician Assistants and is the Director of Zeta 21, the Hayes International Leadership Scholarship Foundation. When Mr. Hayes is not in surgery assisting our surgeons, he can be found on the Thunderbird high school basketball court, coaching the boys’ varsity basketball team.


Cynthia J. Shively, M.S.N., FNP-BC

Chief Executive Officer

Ms. Shively is the Chief Executive Officer of Valley Surgical Clinics & Acute Care Surgical Specialists. Cynthia earned her Bachelors of Science degree in Nursing from Chamberlain College of Nursing in St. Louis, MO, Honors: Magna Cum Laude. She obtained her First Assistant certification from Perioperative Associates at Gateway College in 2004. She went on to become Certified Nurse of the Operating Room in 2004. Cynthia completed her Master degree in Nursing with her Family Nurse Practitioner degree from Saint Louis University and graduated with distinction; Summa Cum Laude.  Ms. Shively is an active member American College of Nurse Practitioners and is a long-time member of Sigma Theta Tau International. Her collaboration with the Arizona Dominican Medical Friends, a non-profit surgical group, provides free surgical care to the indigent of the Dominican Republic and works to promote a mentorship program to the operating room nurses in the Dominican Republic.

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