Providers
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James Hayner, MD
Internal Medicine Physician
With nearly 30 years of experience, Dr. Hayner is a highly respected Internist in the Livingston County and SJMH communities. He is certified with the American Board of Internal Medicine (ABIM) and has extensive experience in out-patient, hospitalist, and critical care medicine. Dr. Hayner is well known for his meticulous attention to detail and his clinical interests include the treatment of acute and chronic disease processes, the management of complex medical illnesses, and the promotion of wellness through evidence-based principles.
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Art Szyniszewski, MD, FACC
Cardiologist
Dr. Art Szyniszewski has 35 years of experience in cardiology. He is board certified in internal medicine and cardiovascular disease; and has a specialty board certification in interventional cardiology. Dr. Szyniszewski was with Michigan Heart for 33 years. He also served as the director of the cardiac cath lab at Saint Joseph Mercy Hospital, and was co-director of their structural heart program. Although Dr. Szyniszewski has retired from interventional work in the cardiac cath lab and hospital, he continues to serve the community through his outpatient practice. His primary focus remains the diagnosis, treatment, and prevention of coronary disease, structural heart disease, arrhythmias, and heart failure. Dr. Szyniszwski enjoys seeing patients in the office and helping them to achieve their optimal cardiac health. He lives in the area with his wife and two sons, and enjoys bicycling, cross-country skiing, skating, music, and reading (especially science and history).
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Chelsea DeLuca, NP
Certified Nurse Practitioner
Chelsea DeLuca is a certified Family Nurse Practitioner at Hayner Internal Medicine Associates. She completed her Master of Science in Nursing degree from the University of Michigan Ann Arbor in 2018. She has worked in an urgent care setting, continuously focusing on primary care prevention while treating acute care needs proficiently. She is also passionate about teaching and works as a Clinical Instructor for the University of Michigan Ann Arbor. Chelsea focuses her interests in multiple areas such as family medicine, treating complex medical comorbidities, and women’s health. She is available for virtual visits and eagerly welcomes new patients.
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Sydney Hattie, DNP, FNP-BC
Doctor of Nursing Practice
Sydney L. Hattie is a board-certified Family Nurse Practitioner. She lives in Dexter with her husband, three children, and her two dogs. She received her bachelor’s degree in nursing from the University of Michigan and continued at Michigan to complete her Doctorate of Nursing Practice (DNP). She enjoys focusing on the prevention and management of chronic diseases to promote the highest quality of life. Sydney is also passionate about patient-centered care and involving the patient in daily health decisions. By providing a patient with evidence-based healthcare options, patients can be supported to make the best health decisions for themselves and their families.
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Haley Dontje, MSN, FNP-C
Nurse Practitioner
Haley Dontje, MSN, FNP-C, is a board-certified Family Nurse Practitioner dedicated to delivering compassionate, evidence-based care. She lives in the Lansing area with her husband and their three children. Haley earned her Bachelor of Science in Nursing from Michigan State University and went on to complete her Master of Science in Nursing at Walden University. Her clinical background spans both cardiology and primary care, equipping her with a well-rounded foundation to support patients across all stages of life. With a strong focus on patient education, Haley empowers individuals to take charge of their health through informed decision-making and preventive care.
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