Meet Our Medical Directors

Jack Casas, MD  |  Peripheral Vascular Services

Dr. Casas is our champion for changing the paradigm in vascular treatment. He has been instrumental in building Mercy Heart & Vascular Institute's vascular program and has dedicated countless hours to educating physicians and the community about modern treatments for vascular disease. He is board certified in Cardiovascular Disease and Vascular Medicine and is a physician trainer for coronary and peripheral laser courses.

Michael Chang, MD  |  Medical Director, Cardiovascular Services

Dr. Chang has been with Mercy since 1991 and has served as our Medical Director since 2001. He leads the Interventional Cardiology Program and Cath Labs, which care for patients with coronary artery disease. Under Dr. Chang's direction, Mercy General has streamlined treatment for heart attack patients, reducing our Door-to-Balloon times to 78 minutes, a full 13 minutes less than the national target of 90 minutes. This is particularly important when time is muscle and can dramatically improve the recovery of the patient.

David Magorien, MD  |  Medical Director, Cardiac Rehabilitation and
Non-Invasive Cardiology Services

Allen Morris, MD  |  Medical Director, Cardiac Surgical Services

Dr. Morris oversees Mercy's cardiac surgery program, which is among the very best in clinical outcomes, highest survival rates and has the largest surgery volume in Northern California. As cardiac surgery has evolved, Dr. Morris has led the introduction of minimally invasive procedures for valve replacement, valve repair and atrial fibrillation.

Padraig O'Neill, MD  |  Medical Director, Electrophysiology Services

Dr. O'Neill has been at Mercy General Hospital since 1997 and served as Medical Director for six years. As medical director of the Electrophysiology (EP) Labs, Dr. O'Neill oversees the care for patients with heart arrhythmias. Under his leadership, the EP lab has grown in volume to be the largest in Northern California, providing our patients with cutting edge procedures for pacemakers, defibrillation and complex ablations. He is also our physician trainer for laser lead extractions, welcoming physicians from around the state and beyond to learn this sophisticated technique at Mercy General Hospital.

Scott Baron, MD  |  Medical Director, Emergency Cardiac Care

Dr. Baron is board certified in internal medicine, cardiovascular disease and interventional cardiology. He has been a long-time leader of cardiac services at Mercy San Juan, entering his 21st year.

 

Jonathan Hemphill, MD  |  Medical Director, Cardiac Cath Lab

 

Peter James, MD  |  Co-Chair, Peripheral Vascular Interventional Committee

Dr. James is board certified in diagnostic radiology and vascular and interventional radiology.

Timothy Lee, MD  |  Chair, Cardiology

Dr. Lee is board certified in internal medicine and cardiovascular disease. He has been with Mercy San Juan since 1997 and with Mercy since 1994.

Nick Majetich, MD  |  Medical Director, Coronary Care Services

Dr. Majetich is board certified in internal medicine, cardiovascular disease and interventional cardiology. He has a member of Mercy San Juan's medical staff since 1988.

Stephen Morrison, MD  |  Medical Director, Cardiac Conditioning/Non-Invasive Cardiology

Dr. Morrison is board certified in internal medicine and cardiovascular disease. He is the senior member of Mercy San Juan's cardiac team, having joined the medical center in 1978.

John Mallery, MD  |  Medical Director, Cardiovascular Medicine

Dr. Mallery is a graduate of UCLA School of Medicine and board certified in cardiovascular medicine from the American Board of Internal Medicine. Following his residency at Oregon Health Sciences University, he completed a cardiovascular fellowship at UC Irvine College of Medicine. For nearly 20 years Dr. Mallery has served as Medical Director of Cardiovascular Medicine at Sierra Nevada Memorial Hospital. In that time he has played an integral role in building the hospital's cardiology department and cardiac rehabilitation program, including elite accreditation of the hospital's Cardiology Department by the Intersocietal Commission for the Accreditation of Echocardiography Laboratories.