Our Team

R. Gregory Credi, M.D.

Dr. Credi is a board-certified general and vascular surgeon with extensive gastrointestinal surgical and laparascopic skills. He is a graduate of the University of Illinois (Urbana-Champaign) and of the University of Illinois College of Medicine. His special interests are bariatrics and breast surgeries. In his free time he enjoys golf, basketball, and spending time with his wife and four children.

Andrew McAfee, M.D.
Medical Director

Dr. McAfee is Medical Director of the Memorial Weight Loss and Bariatric Surgery Center. He received his medical degree from Indiana University School of Medicine and completed his residency at Memorial Family Medicine Residency Program. He also received an MBA from the Kelley School of Business in Bloomington, IN. He is a member of the American Academy of Family Physicians and has received numerous academic scholarships. In his spare time, he enjoys sports, movies and walking his dog Kalia.

Taran Conyers, RN, BSN, CBN
Practice Manager

Taran is a Registered Nurse, Certified Bariatric Nurse and Bariatric Practice Manager with the Memorial Weight Loss and Bariatric Surgery Center as well as a post-op RNY gastric bypass patient. She received a Bachelor's degree in Biology from Saint Mary's College in 1997 and a Bachelor's degree in Nursing in 1999. After nursing school, she worked as a pediatric nurse at Elkhart General Hospital. She is also a freelance graphic designer for several large scrapbooking companies, a mother of twins, and a mother of a newfoundland dog. She enjoys Notre Dame football, decorating, crochet, and gardening.

Denise Imperial

Denise Imperial-Greenhaw, R.D., C.D.
Registered Dietician

Denise is a Registered Dietitian with the Memorial Weight Loss and Bariatric Surgery Center. She earned her dietetics and psychology degrees from Andrews University in Berrien Springs, Michigan.

She is a member of both the Nutrition and Psychology Honor Societies and the Academy of Nutrition and Dietetics. Denise has worked in a variety of clinical settings including bariatric and weight loss, cardiac, geriatrics, intensive care, pediatrics and rehabilitation. She’s the proud mother of two wonderful boys, Nate and Seth. She enjoys reading, music and sunsets.

Karen James

Karen James, ANP-BC, NP-C, MSN, P.T.
Adult Nurse Practitioner

Karen James is an Adult Nurse Practitioner certified by both the American Academy of Nurse Practitioners and the American Nurses Credentialing Center. She received her Bachelor of Science Degree in Nursing at Indiana University and Master of Science Degree in Nursing at Indiana University-Purdue University Indianapolis.

Karen is a member of the National Lipid Association and clinical cholesterol and lipid management. She is certified by the American Council of Exercise as a Personal Trainer and Group Exercise Instructor, as well as by the National Exercise Trainer Association as a Pilates instructor. She is an Intrinsic Coach trainer through Totally Coached.

Timothy Onkka, Ph.D.
Behavioral Medicine

Yvette Wilson, B.S.
Exercise Physiologist

Yvette went to Florida Atlantic University in south Florida (Boca Raton) She has a BS in Exercise Physiology. Yvette has been working at Memorials Outpatient Therapy Services MOTS, in orthopedic patient care and marketing for the past 12 yrs. She has 3 children, Nicholas 8, Marissa 6, and Paige 3 who bring her great joy! They love the beach, bike riding, picnics in the park and playing in the yard! Yvette also loves to cook and the kids love to help!

Suellen Firtl
Office Coordinator

Suellen joined the Bariatrics team as Office Coordinator in March 2009. She has been married for 31 years to a South Bend firefighter and has two children, Sarah and Alex. Suellen enjoys spending time with her family, reading and cooking.