Our Team

​Our Surgeons

Gan DunningtonGan H. Dunnington, MD

Dr. Dunnington is a board-certified cardiothoracic surgeon, specializing in minimally invasive complex cardiac procedures such as the “hybrid” maze for treatment of atrial fibrillation, mitral valve repair and replacements as well as VATS lobectomy for the treatment of lung cancer. Dr. Dunnington received his medical degree from Medical College of Virginia. He completed his residency at Stanford University where he also served as Chief Resident of Surgery. In addition, he also completed a fellowship in cardiothoracic surgery at the University of Virginia.

Prior to joining Adventist Heart Institute, Dr. Dunnington was an assistant professor at Stanford University and assistant director of cardiothoracic surgery at El Camino Hospital—a Stanford University affiliate.


Andreas SakapoulosAndreas Sakopoulos, MD, FACS

Dr. Sakopoulos graduated with highest honors from the University of Pisa, School of Medicine and Surgery. He continued his education in North America, training at internationally acclaimed cardiovascular surgery programs, including Loma Linda University and the University of Toronto. He performs heart surgery, including coronary artery bypass surgery, “off pump” bypass surgery, mitral valve repairs and replacements, aortic valve replacements, pacemakers, as well as surgery for atrial fibrillation. He also has extensive expertise in the surgical and endovascular treatment of thoracic and abdominal aortic aneurysms. He has spearheaded the St. Helena Hospital Endovascular program and performs cutting edge interventions on the entire cardiovascular system.

Dr. Sakopoulos maintains a busy thoracic surgery practice, performing video assisted thoracoscopy, as well as surgery for the treatment of lung cancer and other chest tumors.

Dr. Sakopoulos is a sought after teacher and has authored numerous publications in all of the leading journals of his field.


Our Cardiologists

Stewart AllenStewart Allen, MD, FACC

Dr. Allen brings considerable training and expertise in interventional cardiology. He was trained at Wake Forest University in Winston-Salem, North Carolina and completed fellowships in clinical cardiology, cardiovascular research and interventional cardiology.

Dr. Allen’s expertise includes advanced coronary interventions, peripheral artery interventions, and pacemaker placement. He predominately uses the radial artery for heart catheterizations, a technique that patients have overwhelmingly preferred in clinical trials. In addition to practicing as an interventional cardiologist, Dr. Allen has a strong interest in a patient specific, preventative approach. He has served as a spotlight series speaker for the American Heart Association and has given numerous lectures on preventative health and risk factor modification. He has also been designated as a specialist in clinical hypertension by the American Society of Hypertension. He is board certified in Internal Medicine, Cardiovascular Disease, and Interventional Cardiology. Most recently, he has been appointed Medical Director of Cardiology for the Adventist Heart Institute.


Dr BordeMadhusudan Borde, MD, FACC, FCCP, FACP, FAHA

Dr. Borde brings exceptional training and experience. He earned his medical degree from Gandhi Medical College in Hyderabad, India receiving the highest marks. He completed internships at Gandhi Hospital in Secundrabad, India, and at Prince George’s General Hospital and Medical Center in Cheverly, Maryland. Following his internships, he completed a residency in internal medicine at Prince George’s General Hospital and Medical Center. He then completed a fellowship in cardiology at Northwestern University Medical School in Chicago, Illinois, where he also taught. He previously served as a staff cardiologist and Chief of Non-Invasive Cardiac Laboratories at David Grant United States Air Force Medical Center at Travis Air Force Base in Fairfield, CA. Dr. Borde is board certified in both internal medicine and cardiology.

Dr. Borde has held many leadership roles, including Director of Critical Care, Chief of Medicine and Chief of Staff at Sutter Solano Medical Center in Vallejo, CA.


Peter Chang SingPeter Chang-Sing, MD, FACC

Dr. Peter Chang-Sing has been in clinical practice in cardiology in Santa Rosa since 1991. He received his B.S. in Biological Sciences and M.S. in Electrical Engineering from Stanford University and was then concurrently enrolled in the M.D. program at Yale Medical School and the PhD program at Harvard Medical School where he also taught. He completed his internship in Internal Medicine at New York University Medical Center and his residency in Internal Medicine and fellowships in Cardiology and Clinical Cardiac Electrophysiology at Cedars-Sinai Medical Center in Los Angeles. He is certified by the American Board of Internal Medicine in Internal Medicine, Cardiovascular Disease and Clinical Cardiac Electrophysiology. He is a Fellow of the American College of Cardiology and a Fellow of the Heart Rhythm Society. He is Chief of Cardiovascular Disease and Cardiac Surgery and Medical Director of the Cardiac Electrophysiology Lab at Santa Rosa Memorial Hospital. His practice consists of consultative as well as procedural cardiology, with interests in congestive heart failure, arrhythmia management and coronary artery disease. He enjoys spending time with his wife and two children, traveling, hiking, fishing and Stanford football.


Emily ConwayEmily Conway, MD, FACC

Dr. Emily Conway is a board certified cardiologist who is highly regarded by her peers and patients. Dr. Conway is passionate about women’s heart health and serves on the executive leadership committee for the American Heart Association’s Go Red for Women campaign.

Dr. Conway earned her medical degree from Brown University School of Medicine in Providence, Rhode Island. She completed an internship and residency in internal medicine at Thomas Jefferson University Hospital before completing a fellowship in cardiovascular disease at Lankenau Hospital in Wynnewood, Pennsylvania where she served as Chief Fellow. Prior to joining the Adventist Heart Institute, Dr. Conway was in private practice for 5 years. She is an active member of the American College of Cardiology, Women in American College of Cardiology, American Society of Echocardiography and the American Heart Association, Go Red for Women.


Monica DivakaruniMonica S. Divakaruni, MD

Dr. Monica Divakaruni earned her medical degree from University of California San Francisco School of Medicine in San Francisco, CA. She completed her internship and residency in internal medicine at Stanford University Medical Center, where she served as Chief Resident. In addition, she completed a fellowship in cardiovascular disease and interventional cardiology at Stanford University Medical Center. She is board certified in internal medicine, cardiology and interventional cardiology.

Focusing on innovative treatment options, Dr. Divakaruni keeps at the forefront of new diagnostic testing and the most advanced cardiac catheterization techniques available, including transradial catheterization which provides patients with a shorter, more comfortable recovery and a reduced risk of bleeding.

Dr. Divakaruni is an expert in women’s heart disease and is passionate about providing all aspects of cardiac care – from education to diagnosis and treatment. She is the founder and Medical Director of St. Helena Women’s Heart Center in St. Helena, CA.


L Bing LiemL. Bing Liem, DO, FHRS, FA

Dr. Liem earned his medical degree from Michigan State University College of Osteopathic Medicine where he received the Zandos Award for Outstanding Academic Achievement. He completed his internship and residency in internal medicine and cardiology in Michigan, and furthered his fellowship in cardiology and electrophysiology at Stanford University Medical Center in Stanford, CA. He then became a faculty member at Stanford for 15 years before pursuing a career in private practice. He is board certified in internal medicine, cardiovascular disease and earned a special competency in cardiac electrophysiology.

Throughout his career, Dr. Liem has held many leadership titles including directorship of the arrhythmia program at Stanford University. He currently belongs to the Board of Directors for the Heart and Vascular Institute and Scientific Advisory Board for the Genomic Institute at El Camino Hospital. He has been an investigator in over 60 clinical trials and published peer-reviewed scientific papers. He has also been involved in the development of many medical devices in Silicon Valley. Dr. Liem has a special interest in device-based therapy for arrhythmia and heart failure and in the overall treatment of complex arrhythmias.


Whie OhWhie Oh, MD, FACC, FAIC, NASPE

Dr. Oh received his medical degree from Seoul National University College of Medicine in Seoul, South Korea. After Internships at Red Cross Hospital in Seoul and St. Thomas Hospital in Nashville, Tennessee, Dr. Oh had two residencies at Adventist Health White Memorial in Los Angeles. He is Board certified in Internal Medicine, Cardiovascular Diseases and Interventional Cardiology.


Jeong Sik ParkJeong Sik Park, MD, FACC, FAIC, NASPE

Dr. Park received his medical degree from Seoul National University College of Medicine in Seoul, South Korea. After an Internship and Residency at Seoul National University Hospital, Dr. Park had a Fellowship and Residency at Loma Linda University Medical Center. He is Board certified in Internal Medicine, Cardiovascular Diseases, Nuclear Cardiology and Echocardiography.


David PlossDavid R. Ploss, MD

Dr. David R. Ploss is a board-certified cardiologist with twenty years of active practice experience. He earned his medical degree from Tufts University School of Medicine in Boston, Massachusetts, graduating in 1987. He completed a residency in internal medicine at University of California San Francisco followed by a fellowship in cardiology at California Pacific Medical Center in San Francisco, CA. He then completed a second fellowship in cardiac electrophysiology at the West Los Angeles VA Medical Center in Los Angeles, CA.

Dr. Ploss joins the Adventist Heart Institute after growing the Pacific Heart Group to become the largest cardiology practice in Humboldt County. While a member of the medical community there, he served as Chief of Staff and Director of the Cardiac Catheterization Laboratory. Also, in tandem with the local Community Health Clinic System and St. Joseph Hospital, he helped to develop and direct a community Congestive Heart Failure Clinic in Humboldt County. Prior to this, Dr. Ploss was at the Dayton Heart Center in Dayton, Ohio where he developed the cardiac electrophysiology services.

Dr. Ploss brings with him many years of excellence and experience. He is an active member of the Heart Rhythm Society, American College of Cardiology and the American Medical Association. He is interested in the arts and local politics and previously served as president of the Redwood Art Association.


Jon PortnoffJon S. Portnoff, MD

Dr. Portnoff has been practicing in Ukiah for over 25 years. Dr. Portnoff treats and cares for a patient throughout the cardiac process, whether it be advanced testing to a procedure. Dr. Portnoff is a graduate of American University of the Caribbean. He did his residency at the University of Wisconsin Medical School in Milwaukee, and had his fellowship training at Loma Linda University Medical School before coming to Ukiah.