O. H. "Bud" Frazier is a heart surgeon and director of cardiovascular surgery research at the Texas Heart Institute (THI), best known for his work in mechanical circulatory support (MCS) of failing hearts using left ventricular assist devices (LVAD) and total artificial hearts (TAH). Other positions have included chief of the transplant service at Baylor St. Luke's Medical Center (part of the Catholic Health Initiatives system) in Houston.