Meet The Team

Executive Management / Physician Leadership

Leadership can be hard to define and it means different things to different people. Our leaders set direction and help themselves and others to do the right thing to move forward. To do this they create an inspiring vision, and then motivate and inspire others to reach that vision.

Irv Edwards, M.D., FACEP

Founder & President
Dr. Irv Edwards obtained his Bachelor's Degree from McGill University and his Medical Degree from the University of Calgary in Alberta, Canada. He came to Los Angeles to pursue his interest in Emergency Medicine and interned at Los Angeles County Hospital. After his internship, Dr. Edwards completed his residency in Emergency Medicine at Harbor UCLA Medical Center. Following his residency, Dr. Edwards pursued private practice at a variety of hospital sites in Los Angeles and Orange Counties including Chino Valley Medical Center, Encino-Tarzana Regional Medical Center, La Palma Intercommunity Hospital, Mission Community Hospital, Montclair Hospital Medical Center, Olympia Medical Center, Sherman Oaks Hospital, and Valley Presbyterian Hospital. He was the Director of Performance Improvement at Mission Community Hospital from 1998 – 2003 and he currently serves as the Director of Case Management at Mission Community Hospital and as the Chief of Staff at Chino Valley Medical Center. He is the Director of Emergency Services at Chino Valley Medical Center, Encino-Tarzana Regional Medical Center, Mission Community Hospital, and Montclair Hospital Medical Center.

In 1989, Dr. Edwards founded Emergent Medical Associates and has served as its President since inception. Since 2001, Dr. Edwards has been a dedicated member of CAL/ACEP and he currently sits on their Executive Board. He served as its President from 2005-2006.

Mark R. Bell, M.D., FACEP

President
Dr. Mark Bell has been a managing partner in EMA since 1998. Having led the start-up and management of 9 of EMA sites, he has developed a unique skill set centered on creating department efficiencies and managing the critical role emergency departments serve in driving hospital profit. He is currently the Director of Emergency Services at Sherman Oaks Hospital, Valley Presbyterian Hospital, Huntington Beach Hospital and Alvarado Medical Center. He developed the EMA administrative residency program which prepares EMA physicians for administrative roles. His expertise covers customer service, strategic planning, business development, and community service. Dr. Bell is an active physician, hospital advocate, and represents his colleagues in issues on a regional and national level.

Dr. Mark Bell is a graduate of The Chicago Medical School. His undergraduate training was in Santa Barbara, California, at Westmont College. He completed his residency in Emergency Medicine at UC Irvine Medical Center in 1996, and since that time has been in private practice. He’s a fellow of the American College of Emergency Physicians, and has been a managing partner in EMA since 1998. Mark has participated in the growth and development of the emergency medicine division of the company, as well as the establishment of a hyperbaric/wound program, an outpatient family medical center, and most recently the Benchmark Hospitalist program. His expertise is particularly strong in ED and in-patient efficiencies, customer service, paramedic outreach, strategic planning, and business development. Dr. Bell spends much of his time teaching emergency physicians skills in administrative management and emergency medicine leadership. He’s published articles on an array of topics such as pediatric cardiology, nutrition, and EM reimbursement, and frequently lectures on subjects most interesting to him such as The History of Nuclear Biological and Chemical Warfare, EMTALA, and the Field Management of the Unknown Overdose.

Val Warhaft, M.D., ABEM

Chief Risk Officer
Dr. Val Warhaft received his Doctorate of Medicine from the University of Calgary, Alberta, Canada in 1977. His internship was completed at USC Medical Center, followed by a residency in Emergency Medicine at Harbor-UCLA Medical Center. Dr. Warhaft is Board Certified by the American Board of Emergency Medicine and has been a Fellow of the American College of Emergency Medicine since 1982. He has been affiliated with and privileged at facilities such as Memorial Medical Center of Long Beach, Cedar's Sinai Medical Center, Daniel Freeman Memorial Hospital, South Bay Medical Center, Mission Community Hospital, and Medical Center of North Hollywood.

In addition to having chaired or participated on several hospital committees, Dr. Warhaft has served as the director of the Department of Emergency Medicine at Mission Community Hospital of Panorama City, Medical Center of North Hollywood, and South Bay Hospital. His areas of expertise include quality assurance, risk management, emergency department systems and operations. Dr. Warhaft oversees special projects for EMA, and is focused on quality and length of stay improvement at EMA Facilities.

Lee R. Weiss, M.D., FACP, FACEP

Chief Clinical Operations Officer
Dr. Lee R. Weiss is currently Medical Director of Emergency Medical Services at Huntington Beach Hospital and Co-Medical Director of the Department of Emergency Medicine at Centinela Freeman Medical Center in Inglewood, CA.

A graduate of the State University of New York at Downstate School of Medicine, Dr. Weiss trained in Internal Medicine, Immunology, Infectious Diseases, and Emergency Medicine at SUNY Downstate, Kings County Hospital, the National Institutes of Health, SUNY Stony Brook, Bellevue Hospital, and the New York University Medical Center.

Dr. Weiss previously was the Director of Emergency Medical Services at Knox Community Hospital in Mount Vernon, OH, and most recently Vice Chairman of the Department of Emergency Medicine at St. Vincent’s Medical Center in Bridgeport, CT. Dr. Weiss previously held faculty positions in the Departments of Medicine and Emergency Medicine at New York University School of Medicine, The Bellevue Hospital Center, and The Ohio State University School of Medicine.

Dr. Weiss is the founder and previous managing partner of Synergy Micro Systems in Columbus, OH. For the past twenty plus years, Dr. Weiss has focused his research interests on the Epidemiology and Management of Outpatient Infectious Diseases. His major research focus has been the epidemiology of resistance in Streptococcus pneumonia.

An avid international traveler, for the past twenty years, Dr. Weiss has volunteered with Doctors without Borders in Africa and Central Asia. Dr. Weiss resides with his wife Dr. Michelle Weiss and son Gavin in Hermosa Beach, CA.

G. Scott Brewster, M.D., FACEP

Chief Medical Officer
Dr. G. Scott Brewster received his undergraduate training at UC Santa Barbara. He graduated with his medical degree from Northwestern University in Chicago. In 1995 he returned to his native Southern California where he completed both an Internal Medicine and Emergency Medicine Residency at UCLA Medical Center. His final year he acted as Chief Resident for the UCLA/OVMC Residency Program. He is Board Certified in Internal Medicine and Emergency Medicine.

In 2000 he joined the Emergency Department faculty at Olive View - UCLA Medical Center where he served as an Assistant Clinical Professor, UCLA School of Medicine. He was the Director of Critical Care and Director of Medical Student Education. In 2001 he joined the Emergency Department Faculty at Cedars-Sinai Medical Center where he continued his administrative and academic pursuits. He joined EMA in 2003, becoming the Medical Director at the Providence Tarzana Emergency Department. He spent several years as the Director of Recruiting before moving into his current position as the Chief Medical Officer at EMA.

Alan Heilpern, M.D., FACEP

Associate Chief Medical Officer
Dr. Alan Heilpern received his undergraduate degree from the University of California, Los Angeles. He then pursued his medical degree and attended the University de Rouen, Faculty de Medicine in Rouen, France for three years and later he returned to the United States to complete his medical degree at Hahnemann University College of Medicine in Philadelphia, PA. He continued on to complete his internship at Wadsworth Veteran's Administration Medical Center in Los Angeles, CA and completed his residency in Emergency Medicine at the University of Chicago Hospitals and Clinics in Chicago.

In 1993, he completed his graduate degree at the University of California in M.P.H., Health Services. He is presently an attending physician at West Los Angeles Veteran’s Administration Medical Center, Encino-Tarzana Medical Center, Kaiser Permanente Medical Center, and La Palma Intercommunity Hospital. He is the Associate Chief Medical Officer at Emergent Medical Associates and the Medical Director of Emergency Services at La Palma Intercommunity Hospital.

Ari L. Nagler

Chief Executive Officer
Ari Nagler has spent the last two decades building high-performing teams and efficient companies in healthcare, service, retail and hi-tech. He's a previous business owner and M&A executive having closed over 50 transactions for himself and his clients. He possessess a B.S. degree with emphasis in Management and Organizational Development, from Cornell University.

Robert Heinemeier

Chief Financial Officer
Robert Heinemeier has extensive C-level experience managing complex acute care hospitals, physician practices, and ambulatory surgery centers as both a CFO and CEO. Robert has significant public and private company experience with acquisitions, financial reporting, and revenue cycle optimization. He started his career at Arthur Andersen, and has worked for such notable companies as Kaiser Permanente, Dignity Health, and Tenet. He holds a Bachelors degree in Accounting and Information Systems with a Master’s degree in Business Administration, from the University of Southern California.

Lee R. Weiss, M.D., FACP, FACEP

Regional Medical Director – L.A., N.M., A.Z.
Dr. Lee R. Weiss is currently Medical Director of Emergency Medical Services at Huntington Beach Hospital and Co-Medical Director of the Department of Emergency Medicine at Centinela Freeman Medical Center in Inglewood, CA.

A graduate of the State University of New York at Downstate School of Medicine, Dr. Weiss trained in Internal Medicine, Immunology, Infectious Diseases, and Emergency Medicine at SUNY Downstate, Kings County Hospital, the National Institutes of Health, SUNY Stony Brook, Bellevue Hospital, and the New York University Medical Center.

Dr. Weiss previously was the Director of Emergency Medical Services at Knox Community Hospital in Mount Vernon, OH, and most recently Vice Chairman of the Department of Emergency Medicine at St. Vincent’s Medical Center in Bridgeport, CT. Dr. Weiss previously held faculty positions in the Departments of Medicine and Emergency Medicine at New York University School of Medicine, The Bellevue Hospital Center, and The Ohio State University School of Medicine.

Dr. Weiss is the founder and previous managing partner of Synergy Micro Systems in Columbus, OH. For the past twenty plus years, Dr. Weiss has focused his research interests on the Epidemiology and Management of Outpatient Infectious Diseases. His major research focus has been the epidemiology of resistance in Streptococcus pneumonia.

An avid international traveler, for the past twenty years, Dr. Weiss has volunteered with Doctors without Borders in Africa and Central Asia. Dr. Weiss resides with his wife Dr. Michelle Weiss and son Gavin in Hermosa Beach, CA.

Jason Greenspan, M.D., FACEP

Regional Medical Director – SFV
Raised in Southern California, Dr. Jason Greenspan received his Bachelor’s degree from the University of California, Berkeley and his MD from the University of Southern California. He then completed his residency training in Emergency Medicine at LAC+USC Medical Center, where he was Chief Resident. Dr. Greenspan is the Associate Director of Emergency Services at Sherman Oaks Hospital, Mission Community Hospital, and was the Assistant Director of Emergency Services at Granada Hills Emergent Medical Associates from June 2003 – December 2003, and Residency Selection Committee from June 2001 – May 2002.

He has an extreme interest in medical education and his teaching responsibilities include the following: Lectures for Emergency Medicine, Grand Rounds (July 1999 – Present), Lectures and Demonstrations for Advanced Cardiac Life Support (July 2000-Present), Lectures for Emergency Medicine Clerkship (June 2001 – June 2002), Lectures for Nursing Staff (June 2003 – Present). His society memberships include the American Academy of Emergency Medicine (2002-2006), American College of Emergency Physicians (1997-Present), and Emergency Medicine Residents Association (1997-2002).

Kelly Unger, M.D.

Regional Medical Director – Orange County
Dr. Kelly Unger received her Bachelor’s degree at UCLA in physiologic science and medical degree from UCLA School of Medicine. She then completed an Emergency Medicine residency at the Jacobi Montefiore Program at Albert Einstein in the Bronx, NY.

She joined EMA upon moving back to Southern California in early 2008. She began administratively as Assistant Director at La Palma Intercommunity Hospital and Huntington Beach Hospital. She is currently the Regional Medical Director for Orange County as of July 2015 and has been the Medical Director for College Medical Center Long Beach since April 2014.

Jordan Cohen, M.D.

Medical Director – Alvarado & San Diego
Dr. Jordan Cohen was born in Israel, but raised in Southern California. He completed undergraduate studies at UC Irvine before attending medical school at UCLA. After a three year residency in emergency medicine at University of Illinois, Chicago, Dr. Cohen returned to California to direct the emergency medicine program at St. Mary's Medical Center, San Francisco as well as attending at various other Bay Area hospitals.

Prior to joining EMA in January 2012, Dr. Cohen also worked as ED attending in several hospitals in New Jersey. Dr. Cohen is currently the medical director of the ED at Alvarado Hospital as well as the regional director for San Diego county. He has held teaching positions at UCSF, UC Irvine and University of Illinois, Chicago.

Walter "Ricky" Bush, M.D., FACEP

Medical Director - Centinela
Dr. Walter Richard Bush Jr. (also known as Ricky) originally hails from Dalton Georgia; Dr Bush attended Vanderbilt University as a Harold Stirling Vanderbilt Scholar graduating with a degree in General Biology and Chemistry. Dr Bush matriculated at the Wake Forest University Medical School (formerly known as Bowman Gray School of Medicine) in Winston-Salem, North Carolina.

In the summer of 1992, Dr Bush moved to California where he completed his residency at Martin Luther King Jr./Charles Drew General Hospital in Los Angeles. Dr. Bush is the Co-Director for the urgent care at the Martin Luther King Multi-Ambulatory Care Center, the Co-Director at Hubert H Humphrey Comprehensive Health Center Urgent Care, the Associate Director of the emergency department of Valley Presbyterian Hospital, and a staff physician at Chino Valley Medical Center.

Jorge Perez, M.D., Diplomat, ABEM

Medical Director – Chino & Montclair
Dr. Jorge Perez was born of immigrant parents from Mexico and grew up in Southern California. He completed his undergrad at UCLA and majored in Psychobiology. He then attended UC San Francisco for medical school. He was then trained and board certified in Emergency Medicine at LA County-USC and was Chief Resident in his last year.

Dr. Perez joined EMA in early 2000 when they took over emergency services at Chino Valley Medical Center. Since then he has worked closely with EMA to make major improvements in the Emergency Departments at Chino Valley Medical Center and Montclair Hospital where he currently hold title of Associate Director at both sites.

Marco Hernandez, M.D.

Medical Director – Encino, Sherman Oaks & Hollywood Pres.
Dr. Marco Hernandez received his Bachelor’s degree in Biology from San Diego State University in 1993. He went on to attend Medical School at Universidad Autonoma De Guadalajara, in Mexico (July 1993 – June 1996). He then received his Doctor of Medicine from Ponce University Hospital in Puerto Rico where he graduated with clinical distinction and continued with his transitional year at Ponce University Hospital where he was Chief Resident. Dr. Hernandez was residency trained in Emergency Medicine at USC+LAC Medical Center and participated in research involving non-invasive cardiac monitoring.

Dr. Hernandez has been a part of Emergent Medical Associates since graduating his residency and his hospital affiliations include Chino Valley Medical Center, Tarzana Regional Medical Center, and Olympia Medical Center. He is currently the Associate Director of Emergency Services at Valley Presbyterian Hospital.

Shahrokh Kohanim D.O., FACEP, FACOEP

Director of Emergency Services – Mission & Hollywood Presbyterian
Dr. Kohanim received his undergraduate degree from California State University Northridge. He then completed his medical degree from University of New England. He then traveled to New York in 1995 and completed his Internship and Emergency Medicine Residency program at St. Barnabas hospital. He is board certified in Emergency Medicine. He joined Emergent Medical Associate part time in 2003 and then full time in 2006. He is currently Director of Emergency Services at Mission Community Hospital and Associate Director of Emergency Services at Hollywood Presbyterian Medical Center. He is a Fellow of American college of Emergency Physician and Fellow of American College of Osteopathic Emergency Physicians.

He is also Director of undergraduate Emergency Medicine Education for medical students rotating in the ER at Hollywood Presbyterian Medical Center.

He is a clinical Faculty of Midwestern University, Arizona College of Osteopathic Medicine and Clinical Assistant Professor of Emergency Medicine at Western University of Health Sciences.

James De la Torre, M.D., MMM, FACEP, FAAEM

Medical Director - West Hills

Natalie Shum, M.D.

Medical Director – West Hills

Brian Ostick, M.D.

Medical Director – Valley Presbyterian

Matt Dugard, M.D.

Medical Director – Huntington Beach

Pranav Kachhi, M.D.

Medical Director - Temecula Valley
Dr. Pranav Kachhi grew up in the city of Los Angeles. He attended college at UCLA and is thereby a die hard Bruin for life! After college, he moved to Philadelphia where he attended Thomas Jefferson for medical school. He then pursued his interest in emergency medicine by attending residency at LAC/USC Medical Center. Upon completion of his residency in 2001, he joined EMA.

He has worked at multiple EMA sites and hospitals and prides himself in being able to function in a variety of emergency department settings. In 2013, he helped open a brand-new hospital, Temecula Valley, where he currently serves as the Medical Director of the Emergency Department. He currently lives in Northern San Diego and is happily married.

Kristy Ontiveros, M.D.

Medical Director – Las Cruces

Josiah Child, M.D.

Medical Director – Los Alamos

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