Brad Hirst is a physician assistant who providers Emergency Care in the Cass Health Emergency Department. He received his Master’s degree in Physician Assistant studies from the University of North Dakota School of Medicine & Health Sciences in 2012.

Elizabeth Fowlkes, PA-C provides care in the Emergency Department at Cass Health. She is BLS, PALS, ACLS and ATLS certified. She is board certified through the NCCPA and is licensed by both Nebraska and Iowa.

She received her Master’s Degree in Physician Assistant Studies from the University of Nebraska Medical Center in Omaha, Nebraska in 2009.

Theresa Bender is a nurse practitioner who providers Emergency Care in the Cass Health Emergency Department. She graduated from the University of Nebraska Medical Center Nurse Practitioner program in 2011.

Amy Petersen is an Advanced Registered Nurse Practitioner in the Cass Health Emergency Department.  She graduated with her Associates of Science in Nursing from Iowa Central Community College in 1995, her Bachelor of Science in Nursing in 2018 from Excelsior College and her Family Nurse Practitioner from Simmons University in 2020. Amy is board certified by the American Academy of Nurse Practitioners.

Dr. Heather Hergott is a physician in the Cass Health Emergency Department. Dr. Hergott completed her training at the Southhampton Hospital’s Residency Program of Social Osteopathic Medicine in Southampton, NY and is a board-certified family physician.  She received her medical degree from Kansas City University of Medicine and Biosciences in 2011.

Dr. Hergott is a member of the American Osteopathic Association and American College of Osteopathic Family Physicians.

Holly Christensen is an Advanced Registered Nurse Practitioner, board certified by the American Nurses Credentialing Center. She graduated from Graceland University in 2007, earning her Master of Science in Nursing, Family Nurse Practitioner. Since that time she has served in Iowa as a Family Nurse Practitioner in the emergency departments at Manning Regional Health Center, Audubon County Hospital, and Myrtue Medical Center.

Shannon Peterson, ARNP, has provided hospitalist care at Cass Health since 2016.  As a hospitalist, she works on the Inpatient Services Unit caring for patients and regularly communicating with each patient’s primary care provider. She previously worked as a nurse practitioner in the Atlantic Medical Center coumadin clinic.  Shannon graduated in May 2014 from Creighton University with her a Doctor of Nursing Practice degree with a dual track in Family Nurse Practitioner and Adult Acute Nurse Practitioner, and is board certified in both areas.  She received her Bachelor of Science in Nursing from Oregon Health Science University.  During her 15 years as a registered nurse Shannon had experience in numerous areas of nursing, including cardiac, medical/surgical, and OB.


Tammy Bireline, RN, ARNP, is board certified in family practice by the American Academy of Nurse Practitioners. Tammy has cared for patients at Cass Health for more than 20 years. Over the course of her career, she has had varied clinical experience in healthcare including Medical/Cardiac Intensive Care at Iowa Methodist Hospital, Emergency Department/Trauma Coordination at Lutheran Hospital-Des Moines and Cass Health, Cardiac Rehab, Wellness, Medical/Surgical, as well as Outpatient Clinics including chemotherapy and infusion services at Cass Health.  She completed her advanced registered nurse practitioner (ARNP) training at Clarkson College in Omaha, Nebraska in 2014.  She has also completed extensive training specific to emergency care, including ER fundamentals, boot camp and procedures courses.