Meet Our Providers

Once you have been referred to see one of our physicians at East Texas Vascular Associates, the real decision comes after you have met and talked with the doctor. We want you to feel completely confident that the Board Certified surgeon taking care of you has the highest degree of knowledge, using the latest innovation in technology, and that they have compassion regarding their patients overall well-being!


S. Edwin Duncan, M.D., F.A.C.S.

Dr. Silas ‘Edwin’ Duncan grew up in West Texas and studied at Texas A&M University for his undergraduate degree.  He initially started out in veterinary medicine before his medical advisor suggested he had a brighter future in people medicine.  He then went to medical school at University of Texas Southwestern Medical School in Dallas.  He did his general surgery residency at University of Texas in San Antonio and then went to Vanderbilt University where he did his vascular surgery fellowship.  Edwin then had the opportunity to serve on the USS Forrestal aircraft carrier as the ship's surgeon where he had the tremendous opportunity to fly in jet airplanes and land on a carrier deck…which is quite an experience!

Edwin arrived in Tyler, Texas, as the first board certified vascular surgeon in East Texas.  He originated the vascular lab at East Texas Medical Center.  Edwin has been in private practice forming the independent vascular surgery group back in the early 1980’s, now known as East Texas Vascular Associates.  

He is a member of several professional and honorary organizations but his most recent achievement was the honor to be elected president of the Texas Surgical Society in 2013, which is the oldest medical organization in Texas formed in 1915. 

His wife of 47 years is the former Betty ‘Twinkle’ Bivens of Longview, Texas.  They have two children, Clay and Claire, and five grandchildren with his daughter living in Fort Worth and his son living in Houston.  Besides his professional activities, he enjoys hunting with his friends and spending time at their family Lake Tyler lake house where he can relax with his grandchildren. 

Edwin finds it a privilege to be in Tyler with this outstanding medical community and be able to add to the continued excellence through our organization. 


D. Brent Kerns, M.D., F.A.C.S.

David ‘Brent’ Kerns was born and raised in Dumas, Texas.  He has been active in the practice of General and Vascular Surgery in Tyler since 1996.  He attended Texas A&M University, graduated from The University of Texas Southwestern Medical School, and then completed a general surgery training program at The State University of New York.  Following this, he finished his training by completing a fellowship in Vascular Surgery at Washington University, Barnes Hospital in St. Louis, Missouri.  He has worked since that time in Tyler, Texas, at East Texas Vascular Associates. 

His areas of interest and clinical practice include laproscopic and minimally invasive general surgery to include large/small bowel surgery, gallbladder and biliary surgery, and cancer surgery.  He also does endocrine surgery for thyroid, parathyroid, spleen and adrenal pathology. 

His vascular practice includes minimally invasive abdominal aneurysm repair, carotid surgery and stenting, as well as the full spectrum of endovascular and open surgical management of upper/lower extremity arterial occlusive disease.  He is certified by the American Board of Surgery in General Surgery and has added qualifications and board certification in Vascular Surgery. 

Brent is a member of the American College of Surgeons, the Society for Vascular Surgery, and the Texas Surgical Society.  He has been recognized by the Consumer’s Research Council as one of America’s Top General and Vascular Surgeons in 2007, 2012, & 2013!

Brent is the married father of four who enjoys spending time with his family, hunting, fishing and working on his bonsai trees during his spare time.


J. Blake Harrison, M.D., F.A.C.S.

Dr. James ‘Blake’ Harrison was born in Baytown, Texas.  He graduated from Texas A&M University College of Medicine in 1987 with honors.  After completing his residency in General Surgery, he furthered his studies in the areas of Colorectal Surgery in 1993 and then Vascular Surgery in 1998. He holds board certifications in all three of these fields.

Due to his respect for education, Blake is an instructor to upcoming P.A. students through the Baylor College of Medicine Physician Assistant Program.  He has been involved in this program for almost 10 years.  Additionally, as a member of several professional associations, he continues to stay abreast of the latest technology to improve the health of his patients. His latest innovative work is using the da Vinci Robotic Surgical System for surgery cases of the gallbladder and colon, allowing for more precision, more effective results, and less minimally invasive treatment which produces faster recovery.

Blake moved to Tyler, Texas in 1998 and joined East Texas Vascular Associates. He married his high school sweetheart, Denise, and they have four children.


David L. Young, M.D., F.A.C.S.

David L. Young was born and raised in Arlington, Texas.  He graduated with a Bachelor of Science and Master’s Degrees from Baylor University.  He then completed his Doctorate of Medicine at Texas A&M Health Sciences Center.  He is Board Certified in General Surgery and a Diplomat of the American Board of Surgery.

David is very involved in several professional organizations.  He is a Fellow of the American College of Surgeons, Fellow of the Texas Surgical Society, member of the Texas Medical Association and serves as the Smith County Medical Society TMA Delegate to the TMA House of Delegates.  David sits on the Smith County Medical Society Board of Directors and is involved in the American College of Surgeons National Surgical Quality Improvement program.  He also is a Master Mason and Noble of Sharon Shrine. 

David is married with two children.  He enjoys all shooting sports, leatherwork, and being active with his family. 



Olivia L.U. Snodgrass, MPAS, PA-C

Olivia Snodgrass was born in Pennsylvania, grew up in Minnesota until she was 10 years old, and then spent the rest of her childhood in Jarrell, Texas.She attended Texas A&M University in College Station, TX and then graduated with honors from Baylor College of Medicine's School of Allied Health Sciences with a Master of Science in Physician Assistant Studies in Houston, TX. She has worked since that time in Tyler, Texas, with East Texas Vascular Associates.

In her capacity at East Texas Vascular Associates, Olivia follows vascular study patients who are being monitored prior to surgical intervention or after the surgical intervention has occurred. She enjoys working with our patient population and is extremely passionate about preventative health. In addition to her clinical interests, Olivia is passionate about health education and community outreach. She currently is working to improve our web presence in hopes of it becoming a resource to patients and community members. She is certified by the National Commission on Certification of Physician Assistants and is licensed by the Texas State Medical Board.

Olivia is a member of the American Academy of Physician Assistants and the Texas Academy of Physician Assistants.

Olivia is newly married to her husband, Andrew. She enjoys spending time with family, friends, and her Yellow Labrador, Samson. In her spare time, she enjoys antiquing, discovering new coffee shops, and exploring new running trails in East Texas! 

View Olivia's Introduction Letter